OBJECTIVE: It has been known that the enzyme deficiency associated with uric acid production is the minor cause of gout. The purpose of this study is to evaluate the role of hypoxanthine- guanine phosphoribosyltransferase (HGPRT) activity deficiency in the development of gout. METHODS: Assay of HGPRT activity was performed on 38 gout patients and 107 controls compromising 82 men and 25 women. In the patients with gout, age of onset, sex, family history of gout, duration of disease, serum uric acid level, and uric acid concentration of 24-hour urine were analyzed. RESULTS: In gout patients and control male group, the HGPRT activity was lowest in the age of forties. But, in female, there was no decreasing tendency with aging. In 4 gout patients, HGPRT activities were severely deficient and their ages of onset were less than 30 years old, and all have a family history of gout. CONCLUSION: In men, the lowest HGPRT activity in the age of forties could be one of the factors that make the onset of gout is highest in the fifth decade of age. The deficiency of HGPRT enzyme and family history of gout are the important factors in the pathogenesis of early onset gout.