B27
Non-Billable

Infectious mononucleosis

Non-Billable / Non-Specific Code

What is Infectious mononucleosis?

ICD-10-CM B27 is the diagnosis code for Infectious mononucleosis. This code falls under the section "Other viral diseases" within Chapter 1 — Certain infectious and parasitic diseases (A00-B99). It is a non-billable/non-specific ICD-10-CM code that should not be used for reimbursement. A more specific sub-code is required for billing. Medical coders and healthcare providers use this code to document and classify diagnoses in electronic health records, insurance claims, and clinical databases.

Coding Guidelines for B27

Always refer to the official ICD-10-CM Tabular List for complete coding guidelines. Ensure documentation supports the specificity of the code selected. When in doubt, consult a certified medical coder or the latest CMS guidelines.

ICD-10-CM Code Hierarchy

Understanding where B27 sits in the ICD-10-CM classification helps ensure proper coding:

Current CodeB27 — Infectious mononucleosis
Sub-Codes 4 entries
B27.0Gammaherpesviral mononucleosisNon-BillableB27.00Gammaherpesviral mononucleosis without complicationBillableB27.01Gammaherpesviral mononucleosis with polyneuropathyBillableB27.02Gammaherpesviral mononucleosis with meningitisBillableB27.09Gammaherpesviral mononucleosis with other complicationsBillableB27.1Cytomegaloviral mononucleosisNon-BillableB27.10Cytomegaloviral mononucleosis without complicationsBillableB27.11Cytomegaloviral mononucleosis with polyneuropathyBillableB27.12Cytomegaloviral mononucleosis with meningitisBillableB27.19Cytomegaloviral mononucleosis with other complicationBillableB27.8Other infectious mononucleosisNon-BillableB27.80Other infectious mononucleosis without complicationBillableB27.81Other infectious mononucleosis with polyneuropathyBillableB27.82Other infectious mononucleosis with meningitisBillableB27.89Other infectious mononucleosis with other complicationBillableB27.9Infectious mononucleosis, unspecifiedNon-BillableB27.90Infectious mononucleosis, unspecified without complicationBillableB27.91Infectious mononucleosis, unspecified with polyneuropathyBillableB27.92Infectious mononucleosis, unspecified with meningitisBillableB27.99Infectious mononucleosis, unspecified with other complicationBillable
Related Codes

Frequently Asked Questions

Is B27 a billable ICD-10-CM code?

No, B27 is a non-billable/non-specific code. You should use a more specific sub-code for billing and reimbursement.

What does B27 mean?

B27 is the ICD-10-CM diagnosis code for "Infectious mononucleosis". It is used by healthcare providers to classify and document this condition in medical records and insurance claims.

What section is B27 in?

B27 is located in Section B25-B34 — "Other viral diseases" within Chapter 1 of the ICD-10-CM Tabular List.

What are the sub-codes of B27?

B27 has 4 sub-code(s) that provide more specific detail: B27.0, B27.1, B27.8, B27.9.

When should I use B27?

Use B27 when the patients documented diagnosis matches "Infectious mononucleosis" and the clinical documentation supports this level of specificity. Always verify with the latest ICD-10-CM guidelines and payer requirements.

People Also Ask

What is the ICD-10 code for Infectious mononucleosis?

The ICD-10-CM code for Infectious mononucleosis is B27.

Can B27 be used for primary diagnosis?

No, B27 is non-billable. Use a more specific sub-code for primary diagnosis billing.

What chapter is B27 in?

B27 is in Chapter 1 of the ICD-10-CM Tabular List.

Is B27 valid for 2026?

Yes, B27 is a valid ICD-10-CM code for the 2026 fiscal year, subject to official CMS updates.

See Also

← PreviousB26.9Mumps without complicationNext →B27.0Gammaherpesviral mononucleosis
Code Details
B27
Infectious mononucleosis
Non-Billable / Non-Specific Code
1 — Certain infectious and parasitic diseases (A00-B99)
B25-B34 — Other viral diseases
2026 ICD-10-CM