Although peroxisome proliferator-activated receptor alpha (PPARalpha) is highly expressed in the heart, the effects of PPARalpha on cardiac remodelling and the underlying mechanisms are unclear. The present study was undertaken to test the hypothesis that PPARalpha activator fenofibrate plays a key role in left ventricular hypertrophic remodelling via the formation of c-fos/c-jun heterodimers in spontaneous hypertensive rats (SHRs). Twenty-four male 8-week-old SHRs were randomly divided into two groups, one group treated with oral saline (n= 10) and another treated with oral fenofibrate (60 mg.kg-1.d-1, n= 14). Ten same-aged Wistar-Kyoto (WKY) rats were selected as a normal control group. Using echocardiography, immunohistochemistry, co-immunoprecipitation, Western blot analysis and real-time RT-PCR, we showed that the left ventricular wall thickness and significantly reduced and left ventricular diastolic function improved in SHRs treated with fenofibrate compared with SHRs treated with saline. Similarly, the excessive collagen deposition and the up-regulation of collagen I, collagen III, c-fos and c-jun seen in SHRs receiving saline were significantly attenuated in SHRs receiving fenofibrate. In addition, fenofibrate markedly decreased the expression of AP-1 and c-fos/c-jun heterodimers (P < 0.01). These results demonstrated that PPARalpha activator fenofibrate may exert a protective effect on cardiac remodelling in SHRs by decreasing the expression of c-fos and c-jun and suppressing the formation of c-fos/c-jun heterodimers, which may further inhibit transcription of the downstream genes involved in the pathogenesis of left ventricular hypertrophy induced by hypertension.