The rat pancreas shows a phospholipase activity in the absence of the tryptic activation of the zymogens. We verified that this activity was not due to the zymogen of the secretory phospholipase. Indeed unlike the prophospholipase, the enzyme responsible for the spontaneous phospholipase activity shows a higher catalytic rate at substrate concentrations higher than the critical micelle concentration. This enzyme has a positional specificity of the A2 type and possesses a molecular weight of about 9,500.