Acute pancreatitis following endoscopic retrograde cholangiopancreatography (ERCP) occurs in 3-18% of patients undergoing either diagnostic or therapeutic ERCP. We prospectively measured urinary trypsinogen activation peptides (TAP) by an automated anti-TAP enzyme-linked immunoassay among 107 patients 4 h after ERCP to determine whether this measurement helps in the early diagnosis of ERCP-induced pancreatitis. Pancreatitis was documented in 10 of 107 patients (9.3%). All episodes were graded as mild. Urinary TAP was not significantly increased. We conclude that measurement of urinary TAP 4 h after ERCP is not helpful in documenting mild ERCP-induced acute pancreatitis.