Patients with gout associated with "partial" deficiency of hypoxanthine-guanine phosphoribosyltransferase have clinically distinctive findings. Since the disorder is inherited as an X-linked recessive trait, all 21 patients herein reviewed are males. Gouty arthritis is severe and frequently begins before 20 years of age. Renal complications are frequent and may be life-threatening; the syndrome may present as renal failure in infancy. One third of the patients have neurologic abnormalities, ranging from epilepsy to spasticity and incoordination. Because of marked overproduction of uric acid, most patients have serum uric acid concentrations over 10 mg/100 ml; urinary uric acid level is also markedly increased. The enzyme deficiency can be detected by assay of red blood cell hemolysates or other tissues. Allopurinol with high fluid intake is recommended for long-term therapy.