Sorbitol was used as a test sugar for the determination of small intestinal transit time (SITT) by means of breath hydrogen test (BHT). After oral administration of 15g sorbitol, breath hydrogen increased markedly (delta H2 > 5 mumol/L) in 26 of 30 subjects. Following ingestion of a mixture of meglucamine diatrizoate and sorbitol by 18 subjects, SITT measured by BHT correlated closely with the simultaneously determined time for the meglucamine diatrizoate in reaching ileo-cecum. The BHT was used to investigate the effect of berberine on SITT in human. SITT in 20 healthy subjects was 71.10 +/- 22.04 min, SITT was significantly delayed to 98.25 +/- 29.03 min after oral administration of the 1.2g of berberine (P < 0.01). This result suggested that the antidiarrheal property of berberine might be mediated, at least in part, by its ability to delay the small intestinal transit.