Abstract: AimTo study the effect of conjugated linoleic acid (CLA) on obese MSG mice with insulin resistance. MethodsAbout four months old, obese MSG mice with insulin resistance were divided into control, CLA and rosiglitazone groups and drugs were administrated ig once a day. Body weights were recorded regularly, insulin and glucose tolerance were tested. In addition, serum insulin and TNF-α concentrations in serum and fat tissues were determined. ResultsCLA was shown to reduce the body weight and fat weight in MSG mice, but can not improve the abnormal insulin and glucose tolerance in these mice. Indeed, the serum insulin and TNF-α concentrations in the fat tissues of the group treated with CLA were higher than those in the models and the insulin sensitivity index was significantly lower than that in the model mice. ConclusionCLA can reduce the body weight of MSG mice, but can not improve the insulin resistance in these mice.