ICD-10 Code F91.9 – Conduct disorder, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F91.9 – Conduct disorder, unspecified
What it is
F91.9 identifies conduct disorder when the chart documents a persistent pattern of behavior that violates rules or the rights of others, but does not specify a subtype. Use the code only when the record supports conduct disorder and no more detailed category is given.
Clinical signs
Clinical features vary; refer to documentation. Commonly recorded behaviors include aggression, destruction of property, deceitfulness, theft, or serious rule violations that are persistent and developmentally inappropriate.
When to use this code
Use F91.9 when the clinician diagnoses conduct disorder but does not document whether it is childhood-onset, adolescent-onset, or another specified form. It also fits when the note confirms conduct disorder yet leaves the subtype unclear. Check documentation for any more specific F91 code before assigning this one.
Do not use for
Do not use this code for oppositional defiant disorder, adjustment problems, or isolated disruptive behavior without a conduct disorder diagnosis. If the record identifies a specific conduct disorder subtype, code that instead.
Coding tip
Choose F91.9 only after confirming the provider documented conduct disorder and did not specify a more precise F91 category.