OBJECTIVE: Symptom decline in attention deficit hyperactivity disorder (ADHD) was examined with different definitions of remission.METHOD: Symptoms in 128 boys were measured five times over 4 years. The prevalences of syndromatic (less than full syndrome), symptomatic (less than subthreshold diagnosis), and functional (full recovery) remission were estimated as a function of age with multivariate logistic regression.RESULTS: Age was significantly associated with decline in total ADHD symptoms and symptoms of hyperactivity, impulsivity, and inattention. Symptoms of inattention remitted for fewer subjects than did symptoms of hyperactivity or impulsivity. The proportion of subjects experiencing remission varied considerably with the definition used (highest for syndromatic remission, lowest for functional remission).CONCLUSIONS: These results indicate that differences in reported remission rates reflect the definition used rather than the disorder’s course. They provide systematic support for the clinical observation that hyperactivity and impulsivity symptoms tend to decline at a higher rate than inattention symptoms.