Aim To investigate the responseness of the fibroblasts from the myocardium infarcted rats to angiotensinⅡ(AngⅡ). Methods With the tissue isolation, cell culture and the uptake rates of 3 H thymidine ( 3 H TdR), 14 C uridine ( 14 C UR) and 3 H proline ( 3 H Pro) representing syntheses of DNA,RNA and collagen protein of isolated fibroblasts (Fbs) from the heart of myocardial infarction (MI) rats and sham operated (SO) which were treated with losartan or captopril for 6 weeks, respectively. Results The uptake rates of 3 H TdR, 14 C UR and 3 H Pro of Fbs from MI group treated with losartan or captopril are not significantly different from those of the SO one, respectively. These effects of AngⅡon Fbs are abolished completely by 1.8 AngⅡand angiotensin antipeptide, but not completely by angiotensin receptor 1 antagonist, losartan. Conclusion The findings suggest that the responsiveness of Fbs to AngⅡ from MI rats treated with either losartan or captopril is significantly lower than that from that from the MI rats. AngⅡ acts on the Fbs from normal or hypertrophied myocardium via not only AT1 receptor, but also other mechanisms involving in the effects of AngⅡ to Fbs.