Abstract: Objective：To elucidate the diagnostic significance of left axis deviation （LAD） in patients（pts） with chronic（＞6 months） left bundle branch block（LBBB）.Methods：we retrospectively studied 56pts in our hospital from 1992.The evaluation included a complete history，physical examination，chest X-ray films，serial 12lead electrocardiograms（ECG），2D-echocardiograms and Doppler studies. Results：23 pts had left axis deviation（LAD）and 33 pts had normal axis without axis deviation.Among LAD pts，9had previous left anterior fascicular block.8pts started with LBBB without axis deviation，but later ECGs showed LBBB with LAD.6pts showed LBBB with LAD when they took ECG examination in our hospital and there were no former ECG recorders as control.Compared with normal axis pts ，the average disease period of hypertension and diabetes mellitus are much longer in LAD pts.There are statistically significant difference in tricuspid valve disease and aortic disease and ventricular enlargement in LBBB with LAD compared to normals.These results show that LBBB with LAD has severe organic heart disease.Conclusion：These findings point to wards a exact clinical significance in LBBB with LAD.Under this condition，the significance of LBBB with LAD should be taken seriously in clinic practice．