Lesch-Nyhan syndrome is a rare X-linked recessive metabolic disorder characterized by developmental delay, hyperuricemia, choreoathetosis, spasticity, mental retardation, and compulsive self-injurious behavior. This disorder results from a complete deficiency of the purine salvage enzyme, hypoxanthine-guanine phosphoribosyltransferase (HGPRT). This syndrome is often misdiagnosed to cerebral palsy and clinical manifestations are usually related to the degree of enzyme deficiency. Complete HGPRT deficiency presents with severe specific neurologic manifestation and nephrolithiasis leading to fatal kidney damage. This report highlighted the importance of clinical awareness leading to early diagnosis and therapy for prevention of the self mutilation and renal failure, even if we couldn't inhibit the progression of neuro-psychotic symptoms. (J Korean Acad Rehab Med 2005; 29: 673-677)