Previous studies on gallbladder motility in Chagas' disease, which is known to be associated with diffuse destruction of intramural neurons, have produced conflicting results. In the present study we reevaluated this question by submitting chronic chagasic patients (n = 18) and controls (n = 12) to a cholescintigraphic study of gallbladder emptying in response to a single intra-venous injection of 60 ng/kg cerulein 90 min after administration of 99mTC-HIDA. Five min. before and immediately before carulein injection, as well as every 5 min. up to 45 min. after the stimulus, images of the gallbladder were obtained with a gamma-camera coupled to a computer. The counts obtained for regions of interest corresponding to the gallbladder, permitted the calculation of the ejection fraction of the organ and the construction of individual gallbladder emptying curves. The ejection fractions values for the total sample of chagasic patients (median 67.8%; variation, 4.0 to 99.0%), although higher than those for the control group (median: 34.2% variation, 13.1 to 88.0%), were not statistically significant (p greater than 0.05). However, analysis of the individual curves for the chagasics permitted identifying 2 subgroups, one of which (n = 9) showed values very similar to those for the controls, whereas the other (n = 9) showed a very rapid and intense gallbladder emptying. It is concluded that impairment of the gallbladder innervation in Chagas' disease may lead to heterogeneous patterns of gallbladder emptying, with some patients being definitely hypersensitive to an exogenous cholecystokinetic agent.