The effect of intraduodenal oleic acid administration on protein synthesis and enzymatic levels in rat pancreas was investigated. Sprague-Dawley rats were sacrificed at 20, 40, 60, and 80 min after intraduodenal oleic acid administration. Ten minutes before sacrifice, the rats were injected with 50 microCi 3H-Phenylalanine intraperitoneally. Amylase (Am), chymotrypsinogen (Chtg), trypsinogen (Tg) and lipase (Li) activities, and 3H-Phenylalanine incorporation to total secretory proteins were determined in pancreas homogenates. Forty minutes after oleic acid administration, the activities of Chtg, Tg and Li were significantly increased (45, 38 and 23%, respectively) above those from control rats. Amylase levels were not modified. Enzyme activities decreased below baseline levels by 60 and 80 min after oleic acid administration. The 3H-phenylalanine incorporation pattern exhibited a peak at 40 min. We conclude that intraduodenal oleic acid administration stimulates intrapancreatic enzyme content in a non-parallel fashion, before enzyme activities decreased below those from control rats. Protein synthesis was similarly affected by intraduodenal oleic acid.