The causes of hyperamylasaemia or pancreatitis, occasionally observed after the endoscopic retrograde cholangio-pancreatographie (ERCP), have been unequivocally identified as pressure, volume and the duration of contrast medium instillation. In a completely pressure free experimental model involving the perifusion of lobes of the pancreas of guinea pigs, a study has now been carried out to investigate the extent to which, in addition to these known causes, the contrast medium itself contributes to the development of enzymatic disorders. It was found that, merely as a result of stimulation through Ceruletid (Takus), the secretion of amylase was increased by more than 400%. Following the addition of 50% contrast medium to the perifusion medium, however, amylase secretion was completely suppressed. The electron-microscopic examination of the perifused pancreatic cells revealed that the contrast medium had a synthesis-enhancing effect on the production of zymogen granules in the cells of the acini, but that, however, throughout the duration of contrast medium perifusion, the extrusion of granules was suppressed. Only after the contrast medium had been washed out, an excessive secretion of amylase was observed. The findings show that, in addition to the increase of intraductal pressure, the contrast medium itself may also be possible causal factor in the development of hyperamylasaemia or pancreatitis.