Primary focal dystonia is an idiopathic neurological disorder causing involuntary muscle contraction. Its pathophysiology probably involves the basal ganglia and cortical-basal pathways. Primary dystonia appears to be associated with significant obsessive-compulsive symptoms, but evidence remains scarce and contradictory. We addressed the following research questions: (1) Do primary dystonia patients have high obsessive-compulsive symptom scores? (2) Are these symptoms more severe in dystonia than in controls with equivalent peripheral neurological disorders? and (3) Is psychopathology different in botulinum toxin-treated and -untreated dystonia patients? This work was a cross-sectional, descriptive, controlled study comprising 45 consecutive patients with primary focal dystonia (i.e., blepharospasm, spasmodic torticollis, or writer's cramp) 46 consecutive patients with hemifacial spasm, cervical spondylarthropathy, or carpal tunnel syndrome, and 30 healthy volunteers. Assessment included the DSM-IV based psychiatric interview, Symptom Checklist 90R, Yale-Brown Obsessive-Compulsive Scale and Checklist, and the Unified Dystonia Rating Scale. Dystonia patients had higher Yale-Brown Obsessive-Compulsive Symptom scores than both control groups. Dystonia patients with obsessive-compulsive symptom scores above cut-off for clinical significance predominantly developed hygiene-related symptoms. Major depression and generalized anxiety disorder were the most frequent psychiatric diagnoses in primary focal dystonia. Obsessive-compulsive disorder frequency was 6.7%. Primary focal dystonia patients have higher obsessive-compulsive symptom scores than individuals with similar functional disabilities resulting from other neurological disorders, suggesting that obsessive-compulsive symptoms in dystonia are not reactive to chronic disability. Dystonic muscle contractions and obsessive-compulsive symptoms may share a common neurobiological basis related to cortical-basal dysfunction. Psychopathology, especially obsessive-compulsive symptoms, should be actively explored and treated in primary focal dystonia.