Aim In order to find out if the effect of polydaccharide Krestin (PSK) in preventing atherosclerosis is somewhat associated with antioxidant enzymes. Methods Applied pyrogallol auto-oxidatioon method to determine activity of superoxide dismutase (SOD). The content of manganese superoxide dismutase (MnSOD) mRNA in mouse peritoneal macrophages was detected through dot hybridization. Results It showed that, PSK could improve SOD activity from 223.7±29.1 to 356.1±9.3 ku/g (P<0.05) and increase the content of MnSOD mRNA in mouse peritoneal macrophages. And actinomycin D or cycloheximide could block the induction of MnSOD by PSK. Conclusion PSK could enhance SOD activity and MnSOD mRNA expression in mouse peritoneal macrophages. PSK might induce MnSOD mRNA transcription through a new protein synthesis pathway. 还原