An effective treatment for amyotrophic lateral sclerosis (ALS) has not yet been found because the pathogenesis of this fatal disease is not well understood. A number of previous studies demonstrated that intermediate-length polyglutamine repeats within the ataxin-2 gene (ATXN2) might be a risk factor among patients with ALS in Western countries. Here, we aim to determine whether this sequence is a risk factor in Eastern Chinese ALS patients. Therefore, 379 unrelated sporadic ALS patients, 15 unrelated familial ALS patients, and 900 neurologically normal controls were studied. The ATXN2 CAG repeats were amplified using polymerase chain reaction. The products were separated on an 8% polyacrylamide gel and confirmed using Sanger sequencing. The results were evaluated using SPSS 17.0. We found that ATXN2 intermediate-length polyglutamine expansions greater than 24 and 27 repeats were associated with sporadic ALS. Our finding supports the hypothesis that ATXN2 plays an important role in the pathogenesis of ALS.