B27 – Infectious mononucleosis
ICD-10-CM 2027 diagnosis code · Other viral diseases
ICD-10-CM code
B27
- Code
B27(claims format:B27)- Description
- Infectious mononucleosis
- Billable
- No – use a more specific code below
- Valid for
- Dates of service October 1, 2026 – September 30, 2027 (FY2027)
- Chapter
- 1. Certain infectious and parasitic diseases (A00-B99)
- Block
- B25-B34 Other viral diseases
Billable codes under B27
B27 is a header code and cannot be used on claims. Choose the most specific code:
- B27.0 – Gammaherpesviral mononucleosisHeader (more codes below)
- B27.1 – Cytomegaloviral mononucleosisHeader (more codes below)
- B27.8 – Other infectious mononucleosisHeader (more codes below)
- B27.9 – Infectious mononucleosis, unspecifiedHeader (more codes below)
Notes for B27
Includes:
- glandular fever
- monocytic angina
- Pfeiffer's disease
Frequently asked questions
What is ICD-10 code B27?
B27 is the ICD-10-CM code for infectious mononucleosis, in the block B25-B34 (Other viral diseases).
Is B27 a billable code?
No. B27 is a header code with more specific child codes; report one of the billable codes listed above.
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.