Alpha-synuclein aggregation and cytotoxicity are widely considered to play a critical role in the process of Parkinson's disease. Heat shock proteins are a large family of cellular protective molecules in most kinds of cells. In this study, we examined the impact of dominant-positive heat shock transcription factor 1 (HSF1) on alpha-synuclein over-expression cellular model of Parkinson's disease. We found that over-expression of alpha-synuclein could form alpha-synuclein immunopositive inclusions and result in cell death; dominant-positive HSF1 dramatically increased the expression of HSP70 in SH-SY5Y cells, and significantly decreased the level and cytotoxicity of alpha-synuclein. Taken together, these data indicate that dominant-positive HSF1 plays an important role in suppressing alpha-synuclein aggregation and toxicity in SH-SY5Y cells. Parkinson's disease which is marked by alpha-synuclein aggregation may be treated by increasing a set of endogenous heat shock proteins.