In this study, the gastric emptying of a liquid fatty meal and the consecutive gallbladder contraction were simultaneously measured by ultrasound in four different age- and sex-related groups of normal subjects: group A, 15 women less than 50 yr (premenopausal); group B, 15 women greater than 50 yr (postmenopausal); group C, 15 men less than 50 yr; and group D, 15 men greater than 50 yr. Apart from a significantly delayed gastric emptying in the premenopausal women, no significant differences in the postprandial relative gallbladder emptying rates were observed between the four study groups. Ninety-five percent of all study subjects had a gallbladder volume reduction of more than 50% after a liquid fatty meal. It is therefore concluded, that 1) endogenous or contraceptive female sex hormones may have a delaying effect on gastric emptying of caloric liquids in the premenopausal state, 2) aging or gender do not significantly influence the fat-induced gallbladder contraction in man, and 3) a 50% residual volume of the gallbladder after a fatty meal should be considered as the upper limit of normal gallbladder contractility (95 percentile of a normal collective).