Abstract: AIM:To explore the mechanism of TGF-β1 or AngII activated cardiomyocyte hypertrophy in regard to Smadpathway. METHODS: Fresh isolated neonatal rat cardiomyocytes induced by normal, TGF-β1 and AngII groups were used to examine the formation of cell pathway. p-Smad2 protein was measured by Western blot. Hypertrophy was measured by PI staining and RNA expressions were detected by real-time PCR. RESULTS: TGF-β1 and AngII induced cardiomyocyte hypertrophy and Smad protein in cardiomyocytes was stimulated by TGF-β1 or AngII. Expression of β-MHC was obviously higher than that in the control group (P<0.01). PI staining of TGF-β1 group and AngII group were significantly increased compared with the control group (P<0.01). Compared with the control group, p-Smad2 proteins in cardiomyocytes were stimulated by TGF-β1 or AngII. In the TGF-β1 group and AngII group there were no significant differences in the peak time. CONCLUSION: TGF-β1 and AngII activate the Smad signaling system in cardiomyocyte hypertrophy in vitro.