Many investigators have observed that renal calcium stones may be associated with uric acid disorders. Prien and Prien [1] noted that patients with gout who had stone disease frequently passed stones which contained or were composed of calcium oxalate. Gutman [2] also observed a high frequency of calcium oxalate stones in patients who had gout; and he called attention to crystallographic studies of Lonsdale [3, 4] which showed that a significant enough structural correspondence existed between crystals of uric acid, sodium hydrogen urate, and calcium oxalate to allow one to grow upon the surface of another or to act for one another as heterogeneous seed nuclei. Dent and Sutor [5], on the other hand, found that patients with calcium oxalate stone disease were hyperuricemic more often than normal subjects were, even though none of the patients had clinical gout. Smith et al [6] made a similar observation and suggested that calcium stone-formers with uric acid disorders represented a significant metabolic subgroup of calcium stone disease.