A case is reported of a 68-year-old woman admitted in the ICU for acute exacerbation of a chronic obstructive respiratory disease. The trachea was intubated and the lungs ventilated mechanically. She received sedation including midazolam and phenoperidine 1 mg.h-1. On the 6th day, she experienced a massive colonic dilation (caecal diameter of 10 cm at X-ray examination). A colonoscopy was performed which showed the absence of obstruction, confirmed the diagnosis of pseudo-obstruction of the colon and allowed a decompression which was inefficient. A new colonoscopic decompression was performed on the 8th day, without prolonged effect. At that time, the patient was given cisapride in her gastric tube (80 mg). This treatment restarted the bowel movements within 48 hours and the caecal diameter decreased immediately to 7 cm. Cisapride was maintained for 10 days and mechanical ventilation for 30 days. No further dilation occurred during this time and the patient was discharged from the ICU. Few cases of Ogilvie's syndrome successfully treated with cisapride have been reported in the literature. The efficacy of this agent for the treatment of Ogilvie's syndrome remains to be assessed in a controlled study.