We investigated the clinical features and gene mutation in a pedigree of spinocerebellar ataxia (SCA). A series of clinical tests was performed including visual examination, retinal angiography, visual evoked potential, electroretinogram and magnetic resonance imaging. Genomic DNA of the family members and normal controls was used for amplification of the (CAG)n repeats of SCA1, SCA2, SCA3, SCA6, SCA7, SCA17 and DRPLA genes by PCR. The number of (CAG)n was determined by 8% denaturing polyacrylamide gel electrophoresis and direct sequencing. The main features of 2 patients were ataxia, visual failure, retinal degeneration, cerebellar and pontine atrophy. A mutation in SCA7 gene was detected, while no mutations were found in SCA1, SCA2, SCA3, SCA6, SCA17 or DRPLA gene. Therefore, this is a pedigree of SCA7. Analysis of the CAG trinucleotide repeat expansion at the SCA7 locus can provide valuable insights into SCA7.