The fasting plasma levels of 9 gastrointestinal regulatory peptides were measured by radioimmunoassay in 13 stable patients with chronic renal failure receiving hemodialysis treatment regularly and compared with those of 10 healthy controls. The plasma concentrations of gastrin-releasing peptide, motilin, neurotensin, pancreatic polypeptide, peptide YY, somatostatin, substance P, and vasoactive intestinal peptide were increased. The plasma level of gastrin was not statistically different from that of the controls (p = 0.077). We conclude that patients with chronic renal failure receiving hemodialysis treatment regularly have increased concentrations of eight of nine measured gastrointestinal regulatory peptides. The elevated levels of gastrointestinal peptides in patients with chronic renal failure may contribute to uremic gastrointestinal symptoms and dysfunctions. It is necessary to make a renal function evaluation before interpreting measured plasma levels of gastrointestinal regulatory peptides.