Purpose: Lesch-Nyhan syndrome (OMIM #300322, LNS) is an X-linked recessive disorder caused by mutations in the HPRT1 gene. Two clinical syndromes are associated with a deficiency in HPRT enzyme activity; complete deficiency leads to the LNS, whereas partial deficiency results in hyperuricemia and severe gouty arthritis. This study aimed to investigate clinical characteristics and mutation spectrum of patients with LNS. Methods: This study included 29 patients from 27 unrelated families who confirmed by mutation analysis of HPRT1. Mutation analysis of HPRT1 were performed in 27 probands and their 11 mothers. Prenatal diagnosis was carried out in 4 cases using chorionic villus sampling. Results: The mean age at diagnosis was 6 months (4 months – 1 year). Most patients manifested hyperuricemia, choreoathetosis, spasticity, compulsive self-mutilation, and mental retardation. Neurological abnormalities included spasticity, dystonia, seizure, developmental delay, and attention deficit and aggressive behavior. The initial clinical feature mimics the spastic type of cerebral palsy in most cases. Uric acid level at diagnosis was 9.0 ± 2.2 mg/dL. Renal involvements such as nephrolithiasis or urinary obstruction were detected in 7 patients. Sanger sequencing of HPRT1 identified private mutations in 27 probands: 9 missense (33.3%), 5 nonsense (18.5%), 3 splice site (11.1%), 6 small insertion/deletion (22.2%), and 3 large deletion (11.1%). The remaining one patient harbored sequence variant in 5’-untralslated region, which significantly reduces the expression of mRNA of HPRT1 gene from skin fibroblast by RT-PCR. Majority of the mutation was inherited from mother (10/11) with a de novo mutation. Prenatal diagnosis identified an affected male fetus and 3 female carrier fetuses. Conclusions: This study described clinical and molecular characteristics of patients with LNS. The clinical diagnosis of LNS should be considered in the male baby with spastic paraplegia and hyperuricemia. Management of LNS is mainly supportive for symptoms for hyperuricemia and spasticity as well as rehabilitation for developmental delay. Most mutations are private with rare de novo mutation. Prenatal diagnosis including pre-implantation diagnosis is critical for the family at risk because of both no effective treatment and poor quality of life.