During 15 min after intraperitoneal injection of 1 mg pilocarpine in vivo in the mouse, the level of diacylglycerol in the pancreas rose from 0.47 to 0.80 μmol per g wet weight. There were increases in the levels of all of the individual fatty acids which were measured in the diacylglycerol pool. The major increases were in palmitic and linoleic acids. These accounted for 65% of the total increase.