In this study, in order to better understand the familial nature of gout, the possible relationship of uric acid, xanthine, hypoxanthine and xanthine oxidase in gout families was investigated. The hypoxanthine and xanthine levels were determined by HPLC analysis; uric acid levels were determined by photometric method. The members of the patient’s family included the gout patient and their relatives with or without gout problems. This study consisted of investigating 27 gout families which consist of 246 people including 64 male non-gout members, 67 male gout patients, 103 female non-gout members, and 12 female gout patients. In addition a control group of 45 normal healthy subject, who on the basis of medical history and uric acid screen, including 21 males and 24 females from a pool of normals which has no immediate family members within two generations suffering from gouty diseases were selected. The data obtained was analyzed with the use of multi-variance statistics to study the relationship between the subjects and of gout families and the normal healthy subjects. The results of this study indicate that hypoxanthine and xanthine are better indicators than uric acid for gout diagnosis, xanthine could be better than even hypoxanthine. Xanthine oxidase is not a relevant parameter in the diagnosis of gout shown in this study. The mean hypoxanthine and xanthine levels in each gout family and in non-gout members of each tout family were significantly higher in all 27 gout families than in normal healthy control subjects. For gout patients in each gout family, excluding gout families 23 and 24, the mean hypoxanthine levels were also significantly higher than in normal healthy control subjects. The mean xanthine levels of gout patients in each gout family were significantly higher in families 1, 6, 9, 17, 19, 20, 23, and 25 than in normal healthy control subjects. For each gout family and the non-gout members of each family, the mean uric acid levels were significantly higher in families 2, 9, 13, 16-19, and 26 than in normal healthy control subjects. When uric acid levels were compared between gout patients in each gout family and normal healthy control subjects, significantly higher levels were found only in families 1, 6, 9, 17, 19, 20, 23, and 25. The higher hypoxanthine and xanthine levels or family gout history were found to be related to high risk of gout. Consequently, gout has high familial incidence and is related to the plasma levels of hypoxanthine and xanthine.