Because altered intestinal motility could be involved in the pathogenesis of small intestine bacterial overgrowth observed in some patients with cirrhosis, we investigated fasting proximal small bowel motility in 16 cirrhotic patients and 8 healthy controls. In addition, the effects of oral tetracycline administration on duodenal motility were investigated in seven cirrhotic patients with evidence of bacterial overgrowth. The mean duration and characteristics of the migrating motor complex were analyzed. Cyclic activity was observed in all healthy controls. It was absent in two cirrhotic patients showing a prolonged phase 2-like pattern. The duration of cycles was significantly longer in the remaining 14 patients with cirrhosis (166 +/- 19 min) compared with controls (81 +/- 14 min; p < 0.02). This difference was caused by a prolonged phase 2 (138 +/- 19 min in patients with cirrhosis vs. 52 +/- 11 min in controls; p < 0.02). Marked changes in the contraction pattern during phase 2 were noted in cirrhotic patients. They were characterized by multiple clusters (frequency, 12 +/- 1/hr; duration, 38 +/- 3 sec) of contractions (frequency, 11 +/- 1 cpm) separated by quiescent periods (duration, 2.4 +/- 0.2 min). This motility profile filled up 58% +/- 8% of the total duration of phase 2, and it was observed in patients with and without bacterial overgrowth. Treatment with tetracycline was followed by only mild modifications, such as a reduction of the fraction of phase 2 occupied by multiple-clustered contractions. In conclusion, an altered proximal small bowel motility has been observed in patients with cirrhosis. These disturbances appear not to be dependent on the presence of bacterial overgrowth.