Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is the most common type of spinocerebellar ataxia in China. However, the pathogenesis of SCA3/MJD is still unknown. MicroRNAs (miRNAs) have been repeatedly demonstrated to exist in human peripheral serum in a bio-stable form and have been shown to be useful biomarkers for other neurodegenerative disorders. However, no study of SCA3/MJD patients has assessed specific changes in regulatory miRNAs. Therefore, we systematically used the miRCURYTM LNA Array, followed by quantitative real-time polymerase chain reaction validation, to access miRNA expression levels in the serums from SCA3/MJD patients. Our results show that miR-25, miR-125b, miR-29a, and miR-34b could be potential biomarkers for SCA3/MJD and could be used to further investigate the pathogenesis of SCA3/MJD and drug development.