Studies of the molecular basis of insulin resistance have focused on the peroxisome proliferator activated receptor gamma (PPARγ, γ1 and γ2). The aim of this study was to determine whether the insulin resistance in liver of diabetic animals is associated with abnormal expression of these receptors. PPARγ mRNA and protein expression levels were quantified in liver of 9weekold male ob/ob mice as a model of diabetes and compared to age and gendermatched wild type control animals of the same genetic background. Semiquantitative reverse transcriptionpolymerase chain reaction, using 18S rRNA as an internal standard, indicated that PPARγ2 mRNA was significantly upregulated in ob/ob liver vs. that in wild type mice. Western blotting revealed greater immunoreactivity of PPARγ2 in liver from ob/ob mice relative to that in wild type mice. An index of insulin resistance (product of serum glucose and insulin concentration) was correlated with liver PPARγ2 mRNA expression (r = 0.776; p < 0.001). The findings that liver PPARγ2 expression is (1) significantly elevated in the ob/ob model of diabetes and (2) positively associated with an index of insulin resistance, suggests a possible compensatory response through which type II diabetic and obese organisms strive to maintain insulin sensitivity of the liver.