Hsp104p, as an anti-oxidative protector of ROS generation, was examined to inquire if it prevents aggregation of synuclein mutants, A30P or A53T upon aging, in vitro. The role of Hsp104p was also addressed in dissociation of pre-formed aggregates of synuclein mutants. Significant protection in fibril formation was observed by wild-type Hsp104p regardless of ATP presence, not by mutant Hsp104p. To a lesser extent, the dissociation effect of wild-type Hsp104p was observed only in the presence of ATP. These results will be discussed in relation to the development of an antioxidant approach to prevent amyloid fibril formation in several neurodegenerative diseases.