We attempted to determine whether the administration of erythromycin shortens the period of postoperative ileus by a prospective, double-blind, placebo-controlled study. Seventy-seven patients were randomized and included in the statistical calculations. The patients were stratified according to the operation performed (cholecystectomy, celiotomy, or other major abdominal operations). Forty-one patients (group 1) received 250 mg erythromycin intravenously every 8 h for nine doses upon admission to the recovery room. Thirty-six patients (group 2) received placebo. The time (in hours) to first passage of flatus, first liquid meal, first bowel movement, and total length of hospital stay was recorded. There was no significant difference between group 1 and group 2 in time to first flatus (54.9 +/- 29 vs. 53.9 +/- 27 h, respectively), first meal (70.4 +/- 44 vs. 71.7 +/- 65), first bowel movement (81.8 +/- 32 vs. 80.1 +/- 28), or length of hospital stay (185.2 +/- 183 vs. 182.1 +/- 163). Erythromycin, in the dosage tested in this study, does not seem to alter clinical parameters of gastrointestinal motility after an abdominal operation. New prokinetic agents may deserve further studies.