OBJECTIVE Altered small bowel motility and a high prevalence of small intestinal bacterial overgrowth (SIBO) has been observed in patients with liver cirrhosis. Our aim was to explore the relationship between motility abnormalities, portal hypertension, and SIBO. METHODS Twenty-four patients with liver cirrhosis were included. Twelve had portal hypertension (PH) and 12 had liver cirrhosis (LC) alone. Child-Pugh score was the same in the groups. Antroduodenojejunal pressure recordings were performed, and noninvasive variceal pressure measurements were undertaken. Thirty-two healthy volunteers served as a reference group. Bacterial cultures were obtained from jejunal aspirates. RESULTS The PH group had a higher proportion of individual pressure waves that were retrograde in the proximal duodenum during phase II (52% vs 13% vs 8% of propagated contractions; p < 0.001) as well as postprandially (49% vs 18% vs 13%; p < 0.01) compared with LC and controls, respectively. Long clusters were more common in PH than in controls (9.1 +/- 2.1 vs 4.9 +/- 0.8; p < 0.05), and a higher motility index in phase III in the proximal and distal duodenum was seen in the PH as compared with the other groups. The mean variceal pressure was 21 +/- 1 mm Hg. Motor abnormalities were not correlated to the level of variceal pressure. Thirty-three percent of the patients in the PH group but none in the LC group had SIBO. CONCLUSIONS Abnormal small bowel motility and SIBO is common in patients with liver cirrhosis with concomitant portal hypertension. Portal hypertension per se might be significantly related to small bowel abnormalities observed in patients with liver cirrhosis.