Hyperamylasemia is a common finding in chronic renal failure (CRF) patients. It has been suggested that the diagnosis of acute pancreatitis in these patients is confirmed when serum amylase activities are greater than three times the upper normal limits. In order to evaluate the frequency, the type, and the hyperamylasemia levels in patients with various degree of chronic renal failure, the total serum amylase (Ta), the pancreatic (Pa) and salivary (Sa) types of serum isoamylases, as well as the urine isoamylases (Tu, Pu, Su, respectively) have been determined by the Phadebas method. Moreover, the levels of serum electrolytes and triglycerides were determined in order to study any relationship between serum electrolytes as well as triglycerides and alpha-amylase activities. We studied 102 patients of whom 33 (group A) had CRF with serum creatinine levels 8.5 +/- 3.1 mg/dL (mean +/- SD), 59 (group B) were receiving chronic hemodialysis, and 10 (group C) were on continuous ambulatory peritoneal dialysis as well as 47 normal individuals. None of the subjects studied had any clinical manifestation of acute pancreatitis. Our results showed that the Ta, Pa and Sa levels of groups A, B, and C were significantly elevated compared to normal subjects. Eighteen patients had Pa activities greater than three times the upper normal limits. In the present study, no relationship between serum electrolytes as well as triglycerides and alpha-amylases was found. In conclusion, hyperamylasemia was a much more common finding in CRF patients than previously reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)