Indirect pancreatic function tests are frequently used in the clinical routine as complementary tools for the diagnosis of chronic pancreatitis (CP) because of their noninvasiveness and simplicity. We analyzed the clinical efficacy and routine application of a modified serum pancreolauryl test (PLT) in the diagnosis and staging of CP. We studied a total of 90 patients with CP diagnosed by endoscopic retrograde pancreatography and 54 patients with extrapancreatic gastrointestinal disorders as controls. Sensitivity and specificity of the serum PLT in the diagnosis of CP were 82% and 91%, respectively, using a value of 4.5 micrograms/ml as cutoff. In the diagnosis of patients with mild to moderate morphological changes of CP, the sensitivity of the serum PLT (52%) was improved by the concomitant analysis of serum pancreatic amylase in a logistic model (70%). Serum PLT closely correlated with the degree of pancreatic ductal abnormalities (p < 0.001), and showed a sensitivity of 81% and specificity of 89% in the staging of CP (mild-moderate vs. marked CP; cutoff 2.5 micrograms/ml). We conclude that the modified serum PLT is a reliable test which should be considered as a first-line option for the diagnosis and follow-up of patients with CP.