Aging has been shown to have an effect on the capacity to differentiate preadipocytes and on the expression of some genes expressed in adipose tissue. The mRNA levels of adipocyte differentiation-related genes were examined in rhesus monkeys (Macaca Mulatta) ranging in age from 7 to 30 years. The effect of aging on the expression of peroxisome proliferator activated receptor γ (PPAR-γ), adipocyte determination- and differentiation-dependent factor 1/sterol regulatory element binding protein 1 (ADD1/SREBP1), CCAAT/enhancer binding protein α (C/EBPα), lipoprotein lipase (LPL), GLUT4 glucose transporter, and adipsin were examined by slot blot analysis. Significant inverse correlations were observed between age and the mRNA levels of PPARγ, ADD1/SREBP1, LPL, and GLUT4. The coordinate downregulation of these genes may be linked to the declining fat mass of senescent animals. There was no correlation between age and the mRNA levels of adipsin. The mRNA levels of these genes were not correlated to body weight or fasting plasma insulin. These findings indicate that aging may have an effect on the adipocyte differentiation program and this effect appears to be gene specific.