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ICD-10-CM 2027 diagnosis code

J21.0Acute bronchiolitis due to respiratory syncytial virus

✓ Billable / specificCC — complication/comorbidity

J21.0 is a valid, billable ICD-10-CM code for acute bronchiolitis due to respiratory syncytial virus. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

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 J21.0

J21.0 is the ICD-10-CM diagnosis code for acute bronchiolitis due to respiratory syncytial virus. It belongs to category J21 (acute bronchiolitis), block J20-J22 (other acute lower respiratory infections) and chapter 10 (diseases of the respiratory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within J21 (acute bronchiolitis), J21.0 is specifically for acute bronchiolitis due to respiratory syncytial virus. Related codes cover due to human metapneumovirus (J21.1), due to other specified organisms (J21.8) and unspecified (J21.9).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 202 (Bronchitis and Asthma with CC/MCC, relative weight 0.9474) and DRG 203 (Bronchitis and Asthma without CC/MCC, relative weight 0.6512), in MDC 04 (Diseases and Disorders of the Respiratory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 466.11 (acute bronchiolitis due to respiratory syncytial virus (RSV)).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Acute bronchiolitis due to RSV

Notes that apply from higher levels

Instructions written at a parent level also apply to J21.0.

› From J21 Acute bronchiolitis
Includes
  • acute bronchiolitis with bronchospasm
Excludes2
  • respiratory bronchiolitis interstitial lung disease (J84.115)

Broader instructions also apply from J20-J22 Other acute lower respiratory infections and Chapter 10: Diseases of the respiratory system.

Alphabetic index entries

3 entries

Terms in the official ICD-10-CM index that lead to J21.0.

Codes whose notes reference J21.0

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 466.11Acute bronchiolitis due to respiratory syncytial virus (RSV)exact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about J21.0

Is J21.0 billable?

Yes. J21.0 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can J21.0 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict J21.0 as a principal diagnosis.

Is J21.0 a CC or MCC?

J21.0 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does J21.0 group to?

J21.0 is used in the MS-DRG v44.0 logic for MS-DRG 202 (Bronchitis and Asthma with CC/MCC) and MS-DRG 203 (Bronchitis and Asthma without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for J21.0?

The CMS General Equivalence Mappings map J21.0 to ICD-9-CM 466.11.