Thiazolidinediones (TZDs) including rosiglitazone (RSG) and pioglitazone (PIO) are synthetic agonists selective for peroxisome proliferator-activated receptor-γ (PPARγ) and have been clinically used to treat type-II diabetes as insulin sensitizers. Recent meta-analyses have shown that TZDs are associated with an increased risk for the development of heart failure. To elucidate the mechanism underlying such a cardiac adverse effect, we used a ¹H NMR-based approach to examine the metabonomic profiles in the cardiac tissues treated with RSG (15 mg/kg body weight/day) or PIO (45 mg/kg/day) for 4 weeks and found that the TZD treatments resulted in a significantly altered metabolic profile in hearts, which was associated with cardiac hypertrophy. Multivariate analysis demonstrated that TZDs led to an accumulation in adenosine monophosphate (AMP) and a depletion of inosine. Consistently, AMP kinase, a signal pathway sensitive to the change in the intracellular concentrations of AMP, was activated in the cardiac tissues from the TZDs-treated rats. Quantitative real-time reverse-transcriptase polymerase chain reaction showed a significant induction of the genes involved in the de novo synthesis of purine nucleotide but a reduction of those for the catabolism. Furthermore, the putative PPAR-responsive elements were identified in the 5′-flanking regions of the TZD-up-regulated genes such as adenylosuccinate synthase gene (Adss) and phosphoribosl pyrophosphate synthetase 1 (Prps1), and the binding of PPARγ to these motifs was confirmed by using chromatin immunoprecipitation assay. In conclusion, these results demonstrated that TZDs induced alterations in purine nucleotide metabolism in rat hearts via transcriptional regulation of the PPARγ-target genes, which may play an important role in the development of cardiac hypertrophy associated with TZDs.