The aim of this study was to determine whether castor oil-induced secretory diarrhea in mice could be ameliorated by nifedipine, a calcium channel blocking agent in mice. Ten animals received nifedipine in a dose of 1 mg/30 g/body weight and another ten animals received only distilled water via an orogastric feeding tube. Fifteen minutes after the administration of the drug or the distilled water, castor oil was given to all animals. The mean body weight loss was found to be higher in the control group than in the nifedipine treated group two hours after the administration of castor oil. These findings indicate that nifedipine may have a therapeutic role in castor oil-induced secretory diarrhea.