HL7 PID Segment: Patient Identification

The PID segment carries who the patient is — identifiers, name, birth date, sex, address, and contact info. It is the demographic anchor of almost every clinical message. Downstream systems match patients on PID-3 (the identifier list) and display PID-5 (the name), so these two fields receive more parsing attention than any others in HL7 v2.

Purpose

PID carries the patient's identifiers, name, birth date, sex, address, and contact information. Systems match patients on the PID-3 identifier list and display the PID-5 name, which makes those two fields the most consumed in all of HL7 v2.

Used in

PID appears in nearly every patient-centric message: ADT (all admit, transfer, and discharge events), ORM/OMG (orders), ORU (results), MDM (documents), SIU (scheduling), DFT (financial), BAR (billing), and VXU (immunizations). See ADT, ORU, ORM, MDM, and SIU.

Field-by-field reference

Source: official HL7 v2-to-FHIR IG. R = required (cardinality min ≥ 1). Repeat = field may repeat. Length pending authoritative v2.5.1 data.

Seq	Name	Data Type	Length	Req	Repeat	Table #	Description
PID-1	Set ID – PID	SI	—	O	—	—	Sequence number when multiple PIDs appear; usually `1`.
PID-2	Patient ID	CX	—	O	—	—	Deprecated single id; superseded by PID-3.
PID-3	Patient Identifier List	CX	—	R	Y	—	One or more patient ids (MRN, SSN, enterprise id). The matching key.
PID-4	Alternate Patient ID – PID	CX	—	O	—	—	Deprecated alternate id.
PID-5	Patient Name	XPN	—	R	Y	HL70200	Legal name (family^given^middle^suffix^prefix). The most-displayed field.
PID-6	Mother's Maiden Name	XPN	—	O	Y	—	Used for identity matching.
PID-7	Date/Time of Birth	DTM	—	O	—	—	Birth date (`YYYYMMDD` or full DTM).
PID-8	Administrative Sex	CWE	—	O	—	HL70001	`M`/`F`/`O`/`U`/`A`/`N`.
PID-9	Patient Alias	XPN	—	O	Y	—	Deprecated; aliases now in PID-5 with name-type.
PID-10	Race	CWE	—	O	Y	HL70005	Patient race.
PID-11	Patient Address	XAD	—	O	Y	—	Home and mailing addresses.
PID-12	County Code	ID	—	O	—	HL70289	Deprecated; use the PID-11 county component.
PID-13	Phone Number – Home	XTN	—	O	Y	—	Home phone or email.
PID-14	Phone Number – Business	XTN	—	O	Y	—	Work phone or email.
PID-15	Primary Language	CWE	—	O	—	HL70296	Preferred language.
PID-16	Marital Status	CWE	—	O	—	HL70002	Marital status.
PID-17	Religion	CWE	—	O	—	HL70006	Religious affiliation.
PID-18	Patient Account Number	CX	—	O	—	—	Account or visit financial id.
PID-19	SSN Number – Patient	ST	—	O	—	—	Deprecated; put SSN in PID-3 with type `SS`.
PID-20	Driver's License Number	DLN	—	O	—	—	Deprecated; use PID-3.
PID-21	Mother's Identifier	CX	—	O	Y	—	Links a newborn to the mother.
PID-22	Ethnic Group	CWE	—	O	Y	HL70189	Patient ethnicity.
PID-23	Birth Place	ST	—	O	—	—	Free-text birth place.
PID-24	Multiple Birth Indicator	ID	—	O	—	HL70136	`Y`/`N`.
PID-25	Birth Order	NM	—	O	—	—	Order in a multiple birth.
PID-26	Citizenship	CWE	—	O	Y	HL70171	Country of citizenship.
PID-27	Veterans Military Status	CWE	—	O	—	HL70172	Military or veteran status.
PID-28	Nationality	CWE	—	O	—	HL70212	Deprecated.
PID-29	Patient Death Date and Time	DTM	—	O	—	—	Date and time of death.
PID-30	Patient Death Indicator	ID	—	O	—	HL70136	`Y`/`N`.
PID-31	Identity Unknown Indicator	ID	—	O	—	HL70136	Patient identity unknown.
PID-32	Identity Reliability Code	CWE	—	O	Y	HL70445	Reliability of demographics.
PID-33	Last Update Date/Time	DTM	—	O	—	—	Last demographic update.
PID-34	Last Update Facility	HD	—	O	—	—	Facility that last updated.
PID-35	Taxonomic Classification Code	CWE	—	O	—	HL70446	Animal species (veterinary).
PID-36	Breed Code	CWE	—	O	—	HL70447	Animal breed (veterinary).
PID-37	Strain	ST	—	O	—	—	Animal strain.
PID-38	Production Class Code	CWE	—	O	Y	HL70429	Animal production class.
PID-39	Tribal Citizenship	CWE	—	O	Y	HL70171	Tribal affiliation.
PID-40	Patient Telecommunication Information	XTN	—	O	Y	—	Consolidated telecom (v2.7+).

Most-used fields

PID-3 Patient Identifier List is a repeating CX. Each value is ID^check-digit^check-scheme^assigning-authority^identifier-type-code. A real example is 123456^^^HOSP^MR~999-99-9999^^^USA^SS. The identifier-type-code (5th component, table HL70203) distinguishes MRN (MR) from SSN (SS) from enterprise id (PI) — get this wrong and you merge the wrong patients.

PID-5 Patient Name is a repeating XPN: family^given^second/middle^suffix^prefix^degree^name-type-code. The 7th component (name-type, HL70200) marks L legal, A alias, M maiden.

PID-7 Date/Time of Birth, PID-8 Administrative Sex, and PID-11 Address round out the core demographic match set.

Version differences (2.3 to 2.8.2)

2.3: PID-19 (SSN) and PID-20 (Driver's License) were live fields. From 2.5 they are deprecated in favor of typed entries in PID-3.
2.4: PID-29/30 (death date and indicator) added.
2.5: identity indicators (PID-31/32) and veterinary fields (PID-35 to PID-38) added.
2.7: PID-40 (consolidated telecom) added; PID-13/14 phone fields begin migrating to it.
Sex coding (PID-8) expanded over versions; map unknown values to U rather than dropping them.

Common mistakes

Reading the wrong PID-3 repetition — assuming the first is the MRN when SSN comes first. Always select by identifier-type-code, not position.
Putting SSN in the deprecated PID-19 instead of PID-3 with type SS.
Collapsing repeating PID-5 names and losing the legal-versus-alias distinction.
Parsing PID-7 as YYYYMMDD only and choking on a full timestamp with timezone.

Examples

Minimal valid PID (Set ID, identifier, name):

PID|1||123456^^^HOSP^MR||DOE^JOHN

Fully-populated PID:

PID|1||123456^^^HOSP^MR~999-99-9999^^^USA^SS||DOE^JOHN^A^^^^L||19800101|M||2106-3^White^CDCREC|123 MAIN ST^^METROPOLIS^IL^60601^USA^H||^PRN^PH^^^555^5551234|^WPN^PH^^^555^5559876|en^English^ISO639|M^Married^HL70002|||ACCT00042

Annotated breakdown (selected fields of the full example):

PID                                   ← segment ID
1                                     ← PID-1  Set ID
                                      ← PID-2  empty (deprecated)
123456^^^HOSP^MR~999-99-9999^^^USA^SS ← PID-3  Identifier List (MRN ~ SSN)
                                      ← PID-4  empty
DOE^JOHN^A^^^^L                       ← PID-5  Name (family^given^mid^^^^type=L legal)
19800101                              ← PID-7  Date of Birth
M                                     ← PID-8  Administrative Sex
2106-3^White^CDCREC                   ← PID-10 Race
123 MAIN ST^^METROPOLIS^IL^60601^USA^H← PID-11 Address (type H = home)

In-context inside an ADT^A04 (register):

MSH|^~&|EPIC|HOSP_A|RECV|HOSP_B|20260609090000||ADT^A04^ADT_A01|MSG2201|P|2.5.1
EVN|A04|20260609090000
PID|1||123456^^^HOSP^MR||DOE^JOHN^A||19800101|M|||123 MAIN ST^^METROPOLIS^IL^60601
PV1|1|O|CLINIC^^^HOSP|||||||MED

In-context inside an ORU^R01 (result):

MSH|^~&|LAB|HOSP_B|EHR|HOSP_A|20260609131500||ORU^R01^ORU_R01|CTRL-9931|P|2.5.1
PID|1||123456^^^HOSP^MR||DOE^JOHN^A||19800101|M
OBR|1||ORD123|CBC^Complete Blood Count^L
OBX|1|NM|718-7^Hemoglobin^LN||13.5|g/dL|13.0-17.0|N|||F

FHIR mapping

Target resources: Patient (primary), plus Account, Appointment, RelatedPerson, Provenance. Official ConceptMap: ConceptMap-segment-pid-to-patient (JSON).

PID field	FHIR target
PID-3 Patient Identifier List	`Patient.identifier`
PID-5 Patient Name	`Patient.name`
PID-6 Mother's Maiden Name	`Patient.extension` (mothersMaidenName)
PID-7 Date/Time of Birth	`Patient.birthDate`
PID-8 Administrative Sex	`Patient.gender`
PID-11 Patient Address	`Patient.address`
PID-13/14 Phone Numbers	`Patient.telecom`
PID-15 Primary Language	`Patient.communication.language`
PID-16 Marital Status	`Patient.maritalStatus`
PID-21 Mother's Identifier	`RelatedPerson`
PID-24/25 Multiple Birth	`Patient.multipleBirth[x]`
PID-29 Death Date	`Patient.deceasedDateTime`
PID-30 Death Indicator	`Patient.deceasedBoolean`
PID-35/36 Taxonomic/Breed	`Patient.extension` (animal)

Local-extension only or not mapped: PID-10 Race and PID-22 Ethnic Group map to local implementation extensions (US Core uses its own race and ethnicity extensions). PID-32/33/34 and PID-38 are not mapped in the IG.

Engine considerations

Always parse PID-3 by identifier-type-code, never by repetition order.
Required in practice: PID-3 and PID-5 are required by the standard; most interfaces also mandate PID-7 and PID-8 for patient matching.
The repetition separator (~) matters in PID-3, PID-5, PID-11, and PID-13 — flattening repetitions silently drops identifiers, aliases, or addresses.
Escape pitfalls: names with apostrophes or ampersands (O'BRIEN, SMITH & SONS) must use escape sequences; a raw & is the sub-component delimiter and will split the name.

How Vorro parses and produces PID

Vorro indexes every PID-3 repetition by assigning-authority and identifier-type so patient matching selects the correct MRN regardless of order. Repeating XPN, XAD, and XTN fields are preserved as arrays end-to-end, and deprecated fields (PID-19/20) are normalized into typed PID-3 entries on the produce side so downstream FHIR Patient.identifier output is clean.

PV1 — the visit segment that accompanies PID in most messages.
NK1 — next of kin and emergency contacts for the patient.
ADT messages — where PID establishes the patient context.

Sources

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