The incidence of urolithiasis was registered in 87 patients with chronic inflammatory bowel disease and compared with that of renal oxalate excretion. All patients were studied while on a standardized diet with fixed amounts of fat, calcium, and oxalate. Pyelography had been performed in all. Nine, or 35%, of 26 hyperoxaluric patients had urolithiasis, compared with 14, or 23%, of 61 patients were normal renal oxalate excretion, the difference being statistically insignificant. No significant difference in urinary oxalate or urinary calcium in stone-formers as compared with non-stone-formers could be demonstrated. Oxalate was a more frequent component of calculi in patients with normal renal oxalate excretion than in patients with hyperoxalura. Thus, we were unable to demonstrate an increased incidence of urolithiasis in patients with hyperoxaluria compared with a control group with normal renal oxalate excretion. Our results cast doubt on the concept that enteric hyperoxaluria per se is the cause of stone diathesis in chronic inflammatory bowel disease.