Enuresis is an embarrassing rare side effect of clozapine treatment. Using single-blind placebo-control design, the antienuretic activity of the calcium channel blocker verapamil (up to 80 mg/day per os, at 21.00 hours) was evaluated in a schizophrenic patient with comorbid obsessive-compulsive disorder (OCD) who developed nocturnal functional enuresis during clozapine treatment. Verapamil (80 mg/day) displayed antienuretic activity. No correlation between the bradycardiac effect and the antienuretic activity of verapamil was detected.