Our objective was to investigate the association between senataxin mutations and sporadic amyotrophic lateral sclerosis (ALS) in Chinese patients. DNA from 45 sporadic ALS patients was screened for mutations in senataxin using polymerase chain reaction (PCR) and direct sequencing. A novel variation, Thr1118Ile, was identified in a 42-year-old individual with sporadic ALS. This variation was not detected in 200 unrelated control individuals. In conclusion, the presence of this variation in a patient with sporadic ALS, and its absence in 200 controls, supports an association between senataxin and sporadic ALS. This study has broadened the mutation spectrum of senataxin and expanded the clinical phenotypes of senataxin mutations.