In previous studies we isolated human pancreatic elastase 1 from intestinal lavage fluids, where it was found to be part of a complex whose major component was cholesterol. The present study involves the isolation and characterization of this elastase 1-sterol complex recovered from feces of healthy subjects and patients whose intestinal microflora were nearly eradicated by antibiotics. Results indicate that elastase 1 essentially is complexed with neutral sterols, i.e., cholesterol, coprostanol, and coprostanone, in a weight ratio of about 1:1.5, corresponding to about 110 molecules of neutral sterols per one elastase 1 molecule. This complex is elutable with water from the solid moiety of the stools. Elastase 1 thus seems to fulfill the important function of maintaining water solubility of neutral sterols at low bile acid concentrations.