Chronic coronary artery stenosis results in patchy necrosis in the dependent myocardium and impairs global and regional left ventricular (LV) function in rats in vivo. The aim of the present study was to compare regional myocardial blood flow (RMBF) and function (F) in poststenotic myocardium using magnetic resonance imaging [MRI] and to compare MRI blood flow changes to histological alterations in order to assess whether or not resting blood flow in the viable poststenotic tissue remains normal. MRI was performed in 11 anesthetized Wistar rats with two weeks stenosis of the left coronary artery. Post mortem, the extent of fibrotic tissue was quantified. Poststenotic RMBF was significantly reduced to 2.21±0.30 ml/min/g compared to RMBF in the remote myocardium (4.05±0.50 ml/min/g). A significant relationship between the poststenotic RMBF (% remote area) and the poststenotic F (% remote myocardium) was calculated (r=0.61, p<0.05). Assuming perfusion in scar tissue to be 32±5 % of perfusion of remote myocardium, as measured in 5 additional rats, and in remote myocardium to be 114±25 % of normal myocardium, as assessed in 5 sham rats, the calculated perfusion in partially fibrotic tissue samples (35.7±5.2% of analyzed area) was 2.88±0.18, whereas measured MRI perfusion was only 1.86±0.24 (p<0.05). These results indicate that resting perfusion in viable poststenotic myocardium is moderately reduced. Alterations in global and regional LV function are therefore secondary to both, patchy fibrosis and reduced resting perfusion.