Abstract: Objective To investigate the effects of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) on the proliferation and collagen synthesis of cultured rat cardiac fibroblasts (CFs). Methods Cultured CFs from neonatal Wistar rats were isolated by trypsinization, treated with Recombinant human TWEAK (rhTWEAK), and examined after 48h. The CFs proliferation was examined by MTT, and the expressions of collagen Ⅰ and Ⅲ mRNA and protein were determined by qRT-PCR. The expression of collagen Ⅰ protein was determined by Western blot. Results rhTWEAK significantly increased the number of CFs and elevated the expression levels of collagenⅠand Ⅲ mRNA and collagenⅠprotein.Conclusion TWEAK can promote proliferation and collagen synthesis of rat CFs.