Z51.11
Encounter for antineoplastic chemotherapy
Z51.11 (also written Z5111) is a billable ICD-10-CM diagnosis code for encounter for antineoplastic chemotherapy. It is part of the FY2027 code set, effective October 1, 2026. It is one of the 8 codes in category Z51 (Encounter for other aftercare and medical care). The Alphabetic Index lists it under 4 entries. Its coding notes include a Code also instruction, 1 Excludes1 entry and 2 Excludes2 entries.
Guidelines tips
From the FY2027 Official Guidelines. ICD10Ref adds no rules of its own.
Aftercare Z codes are not used when treatment is directed at a current, acute disease, or for aftercare of an injury. For an injury, the acute injury code with a 7th character for a subsequent encounter is used.
When the encounter is chiefly for the therapy, the Z51 code is first-listed and the malignancy is a secondary diagnosis. For brachytherapy, the malignancy is first-listed and Z51.0 is not assigned.
Code also
Two codes may be needed to describe the condition. This note gives no sequencing order.
- condition requiring care
Excludes1
Not coded here. The listed conditions generally should not be reported together.
- follow-up examination after treatment (Z08-Z09)
Excludes2
Not included here. Both codes may be reported if the patient has both conditions.
- encounter for chemotherapy and immunotherapy for nonneoplastic condition - code to condition
Also from chapter/block level (1 note)
- follow-up examination for medical surveillance after treatment (Z08-Z09)
Care settings
How CMS programs treat this code. These are CMS claim edits and list entries, not coverage or eligibility rules.
Home Health Primary
Accepted as the primary (principal) diagnosis on a home health claim. The Home Health Grouper assigns it to the Complex Nursing Interventions clinical group.
Source: CMS Home Health Grouper Software v07.2.26, effective October 1, 2026Notes
Also from chapter/block level (3 notes)
- Z codes represent reasons for encounters. A corresponding procedure code must accompany a Z code if a procedure is performed. Categories Z00-Z99 are provided for occasions when circumstances other than a disease, injury or external cause classifiable to categories A00-Y89 are recorded as 'diagnoses' or 'problems'. This can arise in two main ways:
- (a) When a person who may or may not be sick encounters the health services for some specific purpose, such as to receive limited care or service for a current condition, to donate an organ or tissue, to receive prophylactic vaccination (immunization), or to discuss a problem which is in itself not a disease or injury.
- (b) When some circumstance or problem is present which influences the person's health status but is not in itself a current illness or injury.
Alphabetic Index terms
Terms the official Alphabetic Index lists for this code. 4 entries