Objective:  A significant number of patients with obsessive–compulsive disorder (OCD) fail to benefit sufficiently from treatments. This study aimed to evaluate whether certain OCD symptom dimensions were associated with cognitive‐behavioral therapy (CBT) outcome. Method:  Symptoms of 104 CBT‐treated in‐patients with OCD were assessed with the clinician‐rated Yale‐Brown Obsessive–Compulsive Scale symptom checklist. Logistic regression analyses examined outcome predictors. Results:  The most frequent OCD symptoms were aggressive and contamination obsessions, and compulsive checking and cleaning. Patients with hoarding symptoms at baseline (n = 19) were significantly less likely to become treatment responders as compared to patients without these symptoms. Patients with sexual and religious obsessions tended to respond less frequently, although this failed to reach statistical significance (P = 0.07). Regression analyses revealed that higher scores on the hoarding dimension were predictive of non‐response, even after controlling for possible confounding variables. Conclusion:  Our results strongly indicate that in‐patients with obsessive–compulsive hoarding respond poorly to CBT.