The oculocerebrorenal syndrome of Lowe (OCRL) is a rare X-linked multisystem disorder characterized by congenital cataracts, mental retardation, and renal tubular dysfunction. The OCRL1 gene responsible for Lowe syndrome has been mapped to chromosome Xq24-q26. We analyzed two Taiwanese OCRL patients and their families. In Case 1, a splicing mutation (889-11 G --> A) was identified in intron 10 of the OCRL1 gene. The mother is a heterozygous carrier. The 889-11 G --> A mutation results in an abnormal splicing and predicts premature termination of translation. In Case 2, a novel de novo missense mutation (1373G --> A, P458H) was identified in exon 14 of the OCRL1 gene. The missense mutation predicts a substitution in a domain highly conserved among the inositol-5-phosphatase family.