Diminished activity of peroxisome proliferator-activated receptor-γ (PPARγ) may play a role in the pathogenesis of hypertension and vascular dysfunction. To better understand what genes are regulated by PPARγ, an experimental data set was generated by microarray analysis, in duplicate, of pooled aortic mRNA isolated from mice treated for 21 days with a PPARγ agonist (rosiglitazone) or vehicle. Of the 12,488 probe sets present on the array (Affymetrix MG-U74Av2), 181 were differentially expressed between groups according to a statistical metric generated using Affymetrix software. A significant correlation was observed between the microarray results and real-time RT-PCR analysis of 39 of these genes. Cluster analysis revealed 3 expression patterns, 29 transcripts of moderate abundance that were decreased (−93%) to very low levels, 106 transcripts that were downregulated (−42%), and 46 transcripts that were upregulated (+70%). Functional groups that were decreased included inflammatory response (−93%, n = 6), immune response (−86%, n = 7), and cytokines (−82%, n = 7). There was an overall upregulation in the oxidoreductase activity group (+47%, n = 9). Individually, six transcripts in this group were increased (+72%), and three were decreased (−34%). Fourteen of the genes map to regions in the rat genome that have been linked to increased blood pressure, and of 142 upstream regions analyzed, sequences resembling the DNA binding site for PPARγ were identified in 101 of the differentially expressed genes.