The present study investigated the role of calcineurin in angiotensin II（AngII）- induced cardiac myocyte hypertrophy of rats. Method. The primary cardiac myocytes were cultured under the standard conditions. The calcineurin activity in AngII- treated cardiomyocytes was tested by using PNPP;protein synethsis rate was assessed by 3H- leucine incorporation; atrial natriuretic factor（ANF） mRNA level was determined by Northern blot analysis. Cell viability was estimated by lactate dehydrogenase（LDH） levels in cultured medium and by dyed cell numbers. Result. After stimulation of 10

100 and 1 000nmol/L of AngII

calcineurin activities in the cardiomyocytes were increased by 13％

57％ (P Conclusion. During AngII- induced cardiac myocyte hypertrophy

calcineurin signal pathway is activated

and inhibition of the pathway can attenuate AngII- induced cardiac myocyte hypertrophy

which suggests that the calcineurin signal pathway may play an important role in AngII- induced myocardial hypertrophy of rats.