ICD-10-CM 2027 diagnosis code
B27.0Gammaherpesviral mononucleosis
B27.0 is a header code, so it can't be reported by itself. Choose one of the 4 more specific codes beneath it.
Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data
About B27.0
B27.0 is the ICD-10-CM diagnosis code for Gammaherpesviral mononucleosis. It belongs to category B27 (infectious mononucleosis), block B25-B34 (other viral diseases) and chapter 1 (certain infectious and parasitic diseases). It is a header code, so it can't be reported by itself; one of its 4 subcodes must be used instead.
Within B27 (infectious mononucleosis), B27.0 is specifically for Gammaherpesviral mononucleosis. Related codes cover cytomegaloviral mononucleosis (B27.1), other infectious mononucleosis (B27.8) and unspecified (B27.9).
To report this condition, pick the subcode that matches the documentation: B27.00 (without complication), B27.01 (with polyneuropathy), B27.02 (with meningitis) and B27.09 (with other complications).
It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.
Specific codes under B27.0
Coding notes
- Mononucleosis due to Epstein-Barr virus
Notes that apply from higher levels
Instructions written at a parent level also apply to B27.0.
› From B27 Infectious mononucleosis
- glandular fever
- monocytic angina
- Pfeiffer's disease
Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.
Codes whose notes reference B27.0
Code history
- 2016
- 2017
- 2018
- 2019
- 2020
- 2021
- 2022
- 2023
- 2024
- 2025
- 2026
- 2027
- FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
- No changes since FY2016.
Common questions about B27.0
Is B27.0 billable?
- No. B27.0 is a header code. Report one of its more specific subcodes instead.