Objective: To evaluate the association between postoperative acute pancreatitis (POAP) and postoperative complications including postoperative pancreatic fistula (POPF) in patients undergoing PD. Summary background data: Prediction of post-PD morbidity is difficult especially in the early postoperative period when CT scans are not available. Elevated serum amylase and lipase in postoperative day 0 or 1 may be used to define POAP, but existing literature do not agree on whether POAP is significantly associated with POPF. Methods: We analyzed the data obtained from a previously published randomized controlled trial. POAP was defined as elevations in serum amylase above 110 U/L on postoperative day 0 or 1. Clinically relevant POAP (CR-POAP) was defined as elevations in CRP on postoperative day 2 in those with POAP. Postoperative complications including severe complications (Clavien-Dindo ≥ IIIa), POPF, and clinically relevant POPF (CR-POPF; grades B or C) were analyzed. For a robust selection of variables for multivariable analysis, 500 bootstrap samples were drawn from the original data and backward elimination was performed while forcing POAP to be included. Results: In 246 patients, POAP did not show significant associations with total postoperative complications (odds ratio [OR] 0.697; 95% CI, 0.360-1.313; P = 0.271), severe complications (OR 0.647; 95% CI, 0.258-1.747; P = 0.367), and CR-POPF (OR 0.998; 95% CI, 0.310-3.886; P = 0.998) in multivariable analysis. Conclusions: In patients undergoing PD, POAP was not significantly associated with postoperative complications including POPF. Caution should be taken when using POAP as a predictor of POPF.