The objective of this study is to determine the effect of two angiotensin-converting enzyme inhibitors (ACEi) (Enalapril and Captopril), an angiotensin-II receptor inhibitor (Losartan) and a renin inhibitor (Aliskiren) on renin, TGF-β1 and collagen expressions in human lung fibroblast cultures through real-time PCR and ELISA.Normal commercial fibroblasts (CCD25) were exposed to 10(-6) M of enalapril, captopril, losartan, or aliskiren for 6 h. Subsequently, media were recovered and proteins were concentrated; RNA was extracted from the cells. Real time-PCR and ELISA were performed.ACEi and losartan-stimulated fibroblasts showed an increase in the expression of TGF-β1, Collagen-Iα1 (Col-Iα1), and renin (except losartan) vs PolR2A (p < 0.05), and upregulation of TGF-β1 protein (p < 0.01), except with aliskiren.Results show that ACEis and losartan could play a profibrosing role by inducing the overexpression of molecules such TGF-β1 and Collagen.