Abstract: Objective To investigate the effect of white-noise on heart function of guinea pig.Methods The guinea pigs were exposed to white-noise of 95dB or 100dB,4hr a day for 14 days.Then the electrocardiogram(ECG),the changes of myocardiums tructure,the content of malona ldehyde(MDA),and the activity of lacticacid(LDH)were detected.Results After noise exposure,the ECGs of guinea pigs changed obviously with increased heart rate,decreased P-R duration,augmented P wave am plitude,reduced T wave am plitude.The differences were significant.Compared with the control group,ultras tructure a lteration of myoca rdiumin 100dB noise-exposed group was serious and the MDA content and LDH activity were increased significantly(P<0.01).The damage of 95dB noise-exposed group was less serious compared to the 100dB noise-exposed group.Conclusion The results suggested that noise exposure induced guinea pig's cardiac function disorder,myocard iumultrastructure alteration,and the extent of heart changes was related with the intensity of noise exposure.