Data from individual animals were used to identify genes in mouse skeletal muscle whose expression correlated with a known serum marker of skeletal myopathy, creatine kinase activity (CK), after treatment with a peroxisome proliferator-activated receptors (PPAR) agonist, GW610742X. Six genes had correlation coefficients of >or=0.90: Mt1a (metallothionein 1a), Rrad (Ras-related associated with diabetes), Ankrd1 (ankyrin repeat domain 1), Stat3 (signal transducer and activator of transcription 3), Socs3 (suppressor of cytokine signalling 3) and Mid1ip1 (Mid1 interacting protein 1). The physiological function of these genes provides potentially useful information relating to the mechanism of PPAR-induced skeletal myopathy, with oxidative stress and disruption of glycolysis most closely associated with myopathic damage. Some of the muscle genes most highly correlated with serum CK in mice also appear to be good indicators of PPAR-induced myopathy in rat skeletal muscle, demonstrating the translational potential of this approach. This study clearly shows the utility of using correlation analysis as a simple tool for identifying novel biomarkers and investigating mechanisms of toxicity.