Abstract: To characterize the distributions and subtypes of the spinocerebellar ataxias (SCA) in Guangxi region, the SCAl, SCA2, SCA3/MJD, SCA6, SCA7 and SCA12 (CAG)n mutations were analyzed by polymerase chain reaction (PCR) and capillary electrophoresis (CE). The SCA3/MJD mutation was detected in a total of 21 SCA patients and 19 presymptomatic individuals from 6 SCA families and their CAG repeat numbers were 59~70 and 60~73, respectively. No (CAG)n mutations of SCA1, SCA2, SCA6, SCA7 and SCA12 were detected. This study showed that SCA in Guangxi region is mostly SCA3/MJD subtype and the CAG repeats are smaller than those reported in other regions previously.