ABSTRACT.The mechanical properties of the newborn piglet gallbladder were evaluated in both the stimulated and unstimulated states. The pressure-volume relationships, compliance, and the estimated active tension of the gallbladder were determined in 10 newborn piglets (2–7 days of age). Agonist stimulation was achieved by administration of histamine (25 /μg/kg/h) and cholecystokinin (CCK) (60 ng/kg/h). Both histamine and CCK increased the intracholecystic pressure at the 50% resting volume from 12.4 cm H2O to 18.9 and 15.5 cm H2O, respectively. This resulted in a significant (p< 0.05) increase in the active tension. However, no significant changes were observed in the gallbladder compliance after stimulation. These findings characterize the mechanical properties of the normal neonatal gallbladder. The low magnitude of intracholecystic pressure response to agonist stimulation, when compared to adult data, may explain the occurrence of decreased neonatal choledochal bile flow.