In order to investigate the role of renal factors in affecting trypsinogen I metabolism and excretion in chronic pancreatic disease, serum immunoreactive trypsin (IRT), urinary IRT, γ-glutamyltransferase (GGT), α-glucosidase (AGL) and RNase outputs and the molecular size distribution of serum and urine IRT were studied in 8 control subjects, 18 cases with pancreatic cancer, and 23 cases with chronic pancreatitis. Serum chromatography demonstrated that most immunoreactivity eluted as trypsinogen 1. Smaller amounts of immunoreactivity at higher molecular weights were also observed. Urine chromatography displayed both trypsinogen 1 and heavier molecular forms. An inverse linear correlation was noticed between creatinine clearance and serum trypsinogen 1 levels. Multiple regression analysis (urinary IRT output dependent and GGT, AGL, and KNase predictor variables) showed a significant linear correlation. RNase was found to be the most important parameter in explaining urinary IKI' output. Mild variations in the glomerular function seem to be able to influence serum trypsinogen 1 levels. Urinary IRT excretion is principally explained by a distrubance in the tubular reabsorption of low molecular weight proteins, such as RNase.