To investigate the role of calcineurin dependent signal pathway in cardiac hypertrophy of cold stress induced hypertensive rats, 3 months old Wistar rats were exposed to cold (4?2℃) for 4 hours per day for 8 weeks to produce cold stress induced hypertension and cardiac hypertrophy. The systolic blood pressure(SBP), heart rate and hemodynamic parameters were measured using a force transducer.The heart/body weight ratio, CaN activity, CaN, c fos expression protein of cardiac tissure were also investigated. The results showed that SBP and heart rate in cold stress rats were significantly increased than that in nomal rats during the whole experiment( P