PURPOSE To report mutations in the OPA1 gene in Japanese patients with bilateral optic atrophy unassociated with mitochondrial DNA mutations at nt 11778, 3460, and 14484. METHODS Twelve unrelated patients with bilateral optic atrophy and 100 healthy controls were examined. Each exon of the OPA1 gene was amplified by polymerase chain reaction (PCR). All PCR products were sequenced. RESULTS Of the 12 patients, 2 had nonsense mutations of the OPA1 gene (nt 1039G --> T and nt 1096C --> T, leading to Glu347Stop and Arg366Stop, respectively). These nonsense mutations were not found in the 100 healthy controls. Two of the patients had silent mutations of OPA1 gene (nt 1177T --> G and nt 1923G --> A causing no amino acid change). CONCLUSIONS The mutations (Glu347Stop and Arg366Stop) of the OPA1 gene are involved in the pathogenesis of bilateral optic atrophy in Japanese patients.