The effect of oral administration of cholestyramine, neomycine, calcium, and bile acids on intestinal 14C-oxalate absorption and urinary oxalate excretion was assessed in patients with normal or increased ('enteric' hyperoxaluria) urinary oxalate excretion. Cholestyramine, neomycine and acute administration of chenodeoxycholic acid (2.75 g/24 h) did not affect significantly 14C-oxalate absorption or urinary oxalate excretion. Oral administration of calcium markedly reduced 14C-oxalate absorption (88.2%) and urinary oxalate excretion (46%). Calcium-induced reduction of intestinal oxalate absorption was more pronounced in patients with hyperabsorption of oxalate than in subjects with normal oxalate absorption or excretion. Patients on treatment with high doses of chenodeoxycholic acid (1.5-2.0 g/day) for dissolution of cholesterol gallstones had increased oxalate absorption and excretion, patients on long-term treatment with lower doses of chenodeoxycholic acid (0.75-1.0 g/day) exhibited normal absorption or urinary excretion of oxalate. The results do suggest that calcium and bile acids do play an important role in the pathogenesis of 'enteric' hyperoxaluria. It is suggested that the beneficial therapeutic effect of cholestyramine in hyperoxaluria due to ileal resection is rather caused by its bile acid binding property than by direct binding of oxalate within the intestinal lumen.