Fifty-four patients with Wilson's disease were studied with regard to renal stones. Seven of the 45 patients (16 per cent) who underwent roentgenographic procedures of the urinary tract had unequivocal evidence of renal stones. In four of the seven patients with Wilson's disease who had renal stones, the stones were discovered at the time or before the diagnosis of Wilson's disease was made. Of the several possible factors that may predispose patients with Wilson's disease to renal stone formation, the renal tubular acidosis pattern of abnormality in acid-base excretion is probably the most significant. In general, patients with renal stones and unexplained neurologic, bony or hepatic abnormalities should be screened for Wilson's disease by slit-lamp examination, determination of serum copper and ceruloplasmin concentrations, and urinary excretion of copper, particularly if they have relatively alkaline urine. © 1979.