Pancreatic lipase-related protein 1 (PLRP1) was purified from human, canine, porcine and rat pancreatic juices. The four PLRP1s were identified using microsequencing methods after performing gel filtration on Ultrogel AcA-54 followed by chromatography on Heparin-Sepharose cation-exchanger. Polyclonal antibodies specific to human PLRP1 (HPLRP1) were raised in the rabbit using a synthetic decapeptide from HPLRP1. The results of Western blotting analysis showed that these antibodies recognized native HPLRP1 and recombinant HPLRP1 produced by insect cells, and cross-reacted only with rat PLRP1 (RPLRP1). No significant lipolytic activity was observed with native canine PLRP1 and recombinant HPLRP1 on various glycerides, phospholipid and vitamin esters, or on cholesterol esters. It was established for the first time that this protein is secreted in variable amounts by the adult exocrine pancreas of several species.