Z51.1 – Encounter for antineoplastic chemotherapy and immunotherapy

ICD-10-CM 2027 diagnosis code · Encounters for other specific health care

Non-billable header

ICD-10-CM code Z51.1

Code: Z51.1 (claims format: Z511)
Description: Encounter for antineoplastic chemotherapy and immunotherapy
Billable: No – use a more specific code below
Valid for: Dates of service October 1, 2026 – September 30, 2027 (FY2027)
Chapter: 21. Factors influencing health status and contact with health services (Z00-Z99)
Block: Z40-Z53 Encounters for other specific health care
Parent codes: Z51

Billable codes under Z51.1

Z51.1 is a header code and cannot be used on claims. Choose the most specific code:

Notes for Z51.1

Excludes2 (not included here):

encounter for chemotherapy and immunotherapy for nonneoplastic condition - code to condition

Notes inherited from parent codes

Instructional notes at a category or block level apply to every code below it.

Z51 – Encounter for other aftercare and medical care

Excludes1 (not coded here):

follow-up examination after treatment (Z08-Z09)

Code also:

condition requiring care

Block Z40-Z53

Applicable to:

Categories Z40-Z53 are intended for use to indicate a reason for care. They may be used for patients who have already been treated for a disease or injury, but who are receiving aftercare or prophylactic care, or care to consolidate the treatment, or to deal with a residual state

Excludes2 (not included here):

follow-up examination for medical surveillance after treatment (Z08-Z09)

Related codes in Z51

Z51.0 – Encounter for antineoplastic radiation therapyBillable
Z51.5 – Encounter for palliative careBillable
Z51.6 – Encounter for desensitization to allergensBillable
Z51.8 – Encounter for other specified aftercareHeader
Z51.A – Encounter for sepsis aftercareBillable

Frequently asked questions

What is ICD-10 code Z51.1?

Z51.1 is the ICD-10-CM code for encounter for antineoplastic chemotherapy and immunotherapy, in the block Z40-Z53 (Encounters for other specific health care).

Is Z51.1 a billable code?

No. Z51.1 is a header code with more specific child codes; report one of the billable codes listed above.

What category does Z51.1 belong to?

It belongs to category Z51 – Encounter for other aftercare and medical care.

Source: CDC/NCHS ICD-10-CM FY2027 code files, tabular list and index. Reference only – code assignment must follow the official ICD-10-CM guidelines and documentation in the medical record.