Biliary dyskinesia is frequently encountered in clinical practice and is characterized by pain during or after meals. The present study was designed to assess the action of hymecromone in patients with motor disorders of the bile ducts. One hundred twenty-three patients (36 men and 87 women) were enrolled in the multicenter double-blind placebo-controlled study. The mean age was 60.3 years+/-14.2 SD. Diagnosis was dyspepsia in 58 patients, dyskinesia in 59, cholelithiasis in five and hepatopathy in one. The patients were divided into two groups. One group (61 patients) was treated with hymecromone (300 mg tablets at a dosage of 1,200 mg/day, 2 tablets midday and evening) and another group (62 patients) was treated with placebo. Treatment lasted for 14 days. Control of dyspepsia and pain symptoms of biliary origin was more marked and constant with hymecromone than with placebo. By the end of the treatment, patients in the hymecromone group showed a 70.3% reduction in intensity of spontaneous abdominal pain, while the placebo group showed a 43.8% reduction. Hymecromone was well accepted by the patients and judged to be effective by the investigator in 88.5% of patients treated. The possibility of using hymecromone in 300-mg tablets in the treatment of motor disorders of the bile ducts is thus confirmed.