Background Misophonia is a psychiatric disorder in which ordinary human sounds like smacking or chewing provoke intense anger and disgust. Despite the high burden of this condition, to date there is no evidence-based treatment available. In this study we evaluated the efficacy of cognitive behavioral therapy (CBT) and investigated whether clinical or demographic characteristics predicted treatment response. Methods Ninety patients with misophonia received eight bi-weekly group CBT sessions. Treatment response was defined as a Clinical Global Impression – Improvement Scale (CGI-I) score at endpoint of 1 or 2 (very much or much improved) and a 30% or greater reduction on the Amsterdam Misophonia Scale (A-MISO-S), a measure of the severity of misophonia symptoms. Results Following treatment 48% (N=42) of the patients showed a significant reduction of misophonia symptoms. Severity of misophonia and the presence of disgust were positive predictors of treatment response. Limitations The A-MISO-S is not a validated scale. Furthermore, this was an open-label study with a waiting list control condition. Conclusions This is the first treatment study for misophonia. Our results suggest that CBT is effective in half of the patients.