Antioxidant activities of sliver carp scale collagen peptides -SCSCP- were investigated. SCSCP was separated by ultrafiltration using the Omega membranes with molecular weights cut-off of 5, 3, and 1ku. Antioxidant activities of ultrafiltration fractions were evaluated using six in vitro methods. The results showed that the fraction with molecular weight less than 1 ku -SCSCP-IV- had the significantly - P <0 05- highest antioxidant activities. The SCSCP-IV fraction had higher hydrophobic amino acids and arginine contents, which might be contributed to the higher antioxidant activities. Meanwhile, the SCSCP-IV fraction could significantly - P<0 05- increase the activities of serum antioxidant enzymes SOD and GSH-Px and decrease the MDA content. The results showed the SCSCP-IV fraction had both in vitro and in vivo antioxidant activities.