Human cytochrome P450 (CYP) 2J2 is abundant in heart and active in the biosynthesis of epoxyeicosatrienoic acids (EETs). Recently, we demonstrated that these eicosanoid products protect the myocardium from ischemia-reperfusion injury. The present study utilized transgenic (Tr) mice with cardiomyocyte-specific overexpression of human CYP2J2 to investigate protection towards toxicity resulting from acute (daily dose of 0, 5 or 15 mg/kg for 3 days, followed by a 24 hour recovery) or chronic (biweekly doses of 0, 1.5 or 3.0 mg/kg for 5 weeks, followed by 2 weeks recovery) doxorubicin (DOX) administration. Acute treatment resulted in marked elevations of serum lactate dehydrogenase and creatine kinase levels that were significantly greater in wild type (WT) than CYP2J2 Tr mice. Acute treatment also resulted in less activation of stress response enzymes in CYP2J2 Tr mice (catalase: 750 vs. 300% of baseline; caspase-3: 235 vs. 165% of baseline in WT vs. CYP2J2 Tr mice respectively). Moreover, CYP2J2 Tr hearts exhibited less DOX-induced cardiomyocytes apoptosis (measured by TUNEL) compared to WT hearts. Following chronic treatment, comparable decreases in body weight were observed in WT and CYP2J2 Tr mice. However, cardiac function, assessed by measurement of fractional shortening using M-mode transthoracic echocardiography, was significantly higher in CYP2J2 Tr hearts vs. WT hearts following chronic doxorubicin treatment (WT 37±2%; CYP2J2 Tr 47±1%). WT mice also had larger increases in b-myosin heavy chain (bMHC) and cardiac ankryin repeat protein (CARP) compared to CYP2J2 Tr mice. CYP2J2 Tr hearts had a significantly higher rate of DOX metabolism compared to WT mice (2.2±0.25 vs. 1.6±0.50ng/min/100ug protein). In vitro data from H9c2 cells demonstrated that EETs attenuated DOX induced mitochondrial damage. Together, these data suggest that cardiac-specific overexpression of CYP2J2 limited DOX induced toxicity.