The pancreatic responses of four dogs with pancreatic and gastric fistulae (GF) were studied to intravenous infusion of pentagastrin in doses maximal for gastric acid secretion, and separately to a 400-gramme meat meal. With the GF open a small increase in pancreatic bicarbonate (p < 0.05), and a marked increase in protein output was noted in response to pentagastrin. With the GF closed bicarbonate and protein outputs to pentagastrin (21.5 ± 1.8 SEM/mEq 4 h and 2,305 ± 249 SEM/mg 4 h) were not significantly different from those seen in response to a meat meal (20.6 ± 3.2 SEM/mEq 4 h and 1,884 ± 222 SEM/mg 4 h). These results suggest that when the GF is closed, pentagastrin infusion at doses acid secretion stimulates the pancreas to a degree closely similar to 400-gramme meat meal.