Objective To evaluate the effects of sampling parameters on electrocardiogram (ECG) waveforms inmice. Methods C57 mice were anesthetized with sodium pentobarbital and needle electrodes were placed subcutaneouslyin their limbs. ECG signals were sampled, recorded and analyzed with different sampling parameters using a RM6240BDmulti-channel physiological recording system. Results The sampling rate, low-pass filter, time constant, and notch filterhad different effects on ECG waveforms. Some parameters led to various deformation and distortion of the ECG signals.Conclusions Appropriate sampling parameters should be applied in ECG experiments in mice to obtain accurate results.An improved surgical technique is preferred to acquire stable ECG signals instead of filtering or digital smoothing.