A tubeless pancreatic function test (BTP test) using N-benzoyl-l-tyrosyl-p-aminobenzoic acid was used to assess exocrine function from urinary recovery of p-aminobenzoic acid produced by hydrolysis of the peptide by chymotrypsin. Patients with acute pancreatitis were studied at various time intervals after the acute attack and compared with controls with abdominal pain that was not pancreatic in origin. The initial BTP test carried out in the convalescent period was abnormal in all of 30 patients with acute pancreatitis but normal in 10 patients with non-pancreatic abdominal pain and also in 8 patients who had recovered from an attack of acute pancreatitis 2-6 years previously. Results were improved or normal in 12 of 15 patients re-tested 1 year after the attack of pancreatitis, but 4 out of 6 still had abnormal results 2-6 months after the attack. The data suggest that an attack of acute pancreatitis may impair exocrine pancreatic function for several months.