Type IV collagen is a major component of basement membrane around cardiomyocytes. Arresten, a C-terminal fragment of type IV collagen α1 chain, is highly expressed in heart tissue of normal rats. However, expression of arresten and its role in cardiac hypertrophy have not been determined. In the present study, we investigated the expression of arresten in hypertrophied myocardium of rats with angiotensin II (Ang II)-induced hypertension. In addition, the effect of arresten on Ang II-induced hypertrophy in neonatal rat cardiomyocytes (NRCMs) was examined. We confirmed that an infusion of Ang II (500 ng/kg/min, 4 weeks) induced hypertension and subsequent left ventricular hypertrophy in rats. The expression of arresten in hypertrophied left ventricles tended to be increased. Recombinant rat arresten (100 ng/ml) significantly enhanced Ang II (1 μM, 48 h)-induced hypertrophy in NRCMs. In the present study, we for the first time demonstrate that arresten is upregulated in left ventricles of rats with Ang II-induced hypertension, which might contribute to cardiac hypertrophy.