B27Header code — not billable
Infectious mononucleosis
- Chapter
- 1. Certain infectious and parasitic diseases
- Category
- B27
- Effective date
- October 1, 2026
Related codes in category B27
B27.0Gammaherpesviral mononucleosisB27.00Gammaherpesviral mononucleosis without complicationYesB27.01Gammaherpesviral mononucleosis with polyneuropathyYesB27.02Gammaherpesviral mononucleosis with meningitisYesB27.09Gammaherpesviral mononucleosis with other complicationsYesB27.1Cytomegaloviral mononucleosisB27.10Cytomegaloviral mononucleosis without complicationsYesB27.11Cytomegaloviral mononucleosis with polyneuropathyYesB27.12Cytomegaloviral mononucleosis with meningitisYesB27.19Cytomegaloviral mononucleosis with other complicationYesB27.8Other infectious mononucleosisB27.80Other infectious mononucleosis without complicationYes
Frequently asked questions
What is ICD-10 code B27?
B27 is an ICD-10-CM diagnosis code for Infectious mononucleosis.
Is B27 a billable code?
No. B27 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is B27 in?
B27 falls under Chapter 1: Certain infectious and parasitic diseases.
When did B27 become effective?
B27 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to B27?
B27 belongs to category B27, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.