Objective: To investigate the effects of evodiamine (Evo), a component of Evodiaminedia rutaecarpa (Juss.) Benth, on cardiomyocyte hypertrophy induced by angiotensin II (Ang II) and further explore the potential mechanisms. Methods: Cardiomyocytes from neonatal Sprague Dawley rats were isolated and characterized, and then the cadiomyocyte cultures were randomly divided into control, model (Ang II 0.1 mu mol/L), and Evo (0.03, 0.3, 3 mu mol/L) groups. The cardiomyocyte surface area, protein level, intracellular free calcium ([Ca2+](i)) concentration, activity of nitric oxide synthase (NOS) and content of nitric oxide (NO) were measured, respectively. The mRNA expressions of atrial natriuretic factor (ANF), calcineurin (CaN), extracellular signal-regulated kinase-2 (ERK-2), and endothelial nitric oxide synthase (eNOS) of cardiomyocytes were analyzed by real-time reverse transcription-polymerase chain reaction. The protein expressions of calcineurin catalytic subunit (CnA) and mitogen-activated protein kinase phosphatase-1 (MKP-1) were detected by Western blot analysis. Results: Compared with the control group, Ang II induced cardiomyocytes hypertrophy, as evidenced by increased cardiomyocyte surface area, protein content, and ANF mRNA expression; increased intracellular free calcium ([Ca2+](i)) concentration and expressions of CaN mRNA, CnA protein, and ERK-2 mRNA, but decreased MKP-1 protein expression (P < 0.05 or P < 0.01). Compared with Ang II, Evo (0.3, 3 mu mol/L) significantly attenuated Ang II-induced cardiomyocyte hypertrophy, decreased the [Ca2+](i) concentration and expressions of CaN mRNA, CnA protein, and ERK-2 mRNA, but increased MKP-1 protein expression (P < 0.05 or P < 0.01). Most interestingly, Evo increased the NOS activity and NO production, and upregulated the eNOS mRNA expression (P < 0.05). Conclusion: Evo significantly attenuated Ang II-induced cardiomyocyte hypertrophy, and this effect was partly due to promotion of NO production, reduction of [Ca2+]i concentration, and inhibition of CaN and ERK-2 signal transduction pathways.