A randomized double-blind placebo controlled trial of the safety and efficacy of lidamidine hydrochloride (WHR-1142A) in thirty patients with acute nonspecific diarrhea was conducted. During their 29-hour hospital treatment period, the average number of bowel movements for each ten patient treatment group was: placebo, 5.1: lidamidine hydrochloride (10 mg), 2.4; lidamidine hydrochloride (18 mg), 2.5. The average weight of the feces of the patients in each treatment group was: placebo, 576 grams; lidamidine hydrochloride (10 mg), 364 grams; lidamidine hydrochloride (18 mg), 435 grams. Time intervals between each of the first two doses were greater for those patients in the active treatment groups (lidamidine hydrochloride) when compared to the placebo group. Overall evaluation of therapy was rated by physician and patient at end of study: placebo, 10 of 10, not effective; lidamidine hydrochloride (10 mg), 10 of 10 (100%) effective; lidamidine hydrochloride (18 mg), 10 of 10 (100%) effective. Vital signs and laboratory values remained within normal ranges throughout the duration of study, and no clinically significant adverse effects were reported.