Metabolic status was assessed in 48 patients with nephrolithiasis followed-up for 4 years. Allopurinol and allomaron-treated patients were examined biochemically by 17 parameters of the blood and urine. The effects of the drugs were compared. It is concluded that in hyperuricemia up to 0.37 +/- 0.02 mmol/l allomaron is more effective (1--2 pills a day). In higher hyperuricemia allopurinol is preferable (4 pills a day). Allomaron can be also used (1--2 pills a day) under the control of urinalysis.