Abstract: Objective To investigate the inhibitory effect of fluvastatin on oxidation stress and its relation with lipid decrease in patients with type 2 diabetes mellitus complicated by hyperlipidemia. Methods Forty-one patients（21 males and 20 females with a mean age of 56.7 years）selected from the Affiliated Hospital of Hirosaki University in Japan,were treated with 20mg fluvastastin once a day in the evening for 12 weeks.Changes in plasma LDL,LDL-C,LHPO,and TBARS were assayed at weeks 4,8,and 12 before and after administration of fluvastatin. Results The plasma level of LHPO,TBARS,and LDL-C was 19.4±8.1nmol/mg LDL protein vs 43.3±13.1nmol/mg LDL protein,5.33±0.97nmol/mL vs 8.83±1.11nmol/mL,125±9mg/dL vs 157±12mg/dL,respectively,8 weeks after administration of fluvastatin（P＜0.05）,and 14.4 nmol/mg LDL protein±5.1 vs 43.3±13.1nmol/mg LDL protein,2.3±0.3nmol/mL vs 8.83±1.11nmol/mL,131±5mg/dL vs 157±12mg/dL,respectively,12 weeks after administration of fluvastatin（P＜0.05）.No statistical difference was found in LDL size. Conclusion The levels of LHPO,TBARS and LDL are significantly decreased after administration of fluvastatin,indicating that fluvastatin has inhibitory effect on oxidation in patients with type 2 diabetes mellitus complicated by hyperlipidemia,which is associated with its role in decreasing lipid.