An evaluation of the clinical relevance of an exocrine pancreatic function test in the diagnosis of nonacute pancreatic disease and an analysis of its relationship with morphological data in chronic pancreatitis. The secretin cholecystokinin (S-CCK) test has been used in the diagnosis of nonacute pancreatic disease for many years (Burton, Evans et al, 1960). Because the basal pancreatic secretion is relatively small and highly variable (DiMagno & Go, 1982), stimulation, for instance with exogenous secretin and cholecystokinin, is necessary to obtain sufficient quantities of pancreatic juice from the duodenal lumen for analysis~ Impairment of pancreatic exocrine function, measured in this way, has been demonstrated in diseases like chronic pancreatitis and tumor of the pancreas (DiMagno, 1982). The relatively hidden position of the pancreas prompted clinicians to rely on exocrine function tests for many years. Recently, the introduction of imaging techniques like ultrasound computer scan$ endoscopic retrograde cholangiopancreatography (E.R.C~P.) and selective angiography of the abdominal vessels, have made the pancreas much more accessible for diagnostic purposes. Furthermore, several noninvasive tests of exocrine pancreatic function have been developed such as the Para Amino Benzoic Acid (P.A.B.A.) test (Arvanitakis, 1976). These developments might be anticipated to cause the 'classical' S-CCK test to become outmoded and lose its clinical value for the diagnosis of pancreatic disease$ However, it has become evident that the newer diagnostic modalities also have their limitations, leaving a blind area in the diagnosis especially of early chronic pancreatitis, where pancreatic function tests may provide important clues (Toskes, 1982a). A rising incidence of both chronic pancreatitis (Andersen, Pedersen et al 1982; Hoogendoorn 1978, 1983) and pancreatic cancer (Braganza & Howat, 1979; Kupchik, Reisfeld & Go, 1982) in Western Europe and the USA underlines the importance of adequate diagnostic methods. The poor prognosis of pancreatic cancer, the 'dismal disease', with a 5% 5-year survival rate, is due to the fact that at present only 10% of the patients have potentially curable disease at the time of diagnosis. Early diagnosis may improve survival rate in pancreatic cancer (Morgan & Wormsley, 1977; Moossa, 1982)~ Thus far, the new diagnostic aids have failed to improve the detection rate of pancreatic cancer(Savarino, Mansi et al, 1983). It is clear that there is still room for improvement in the diagnosis of chronic pancreatitis an pancreatic cancer in spite of the introduction of newmethods~ Therefore, we have evaluated the results of S-CCK testing performed in 300 patients between 1975 and 1982 and compared these with the data provided by the imaging techniques mentioned before to find out whether it is still worthwile to perform the S-CCK test nowadays. That is the main issue of this study.