The effect of Bu Zhong Yi Qi Tang (BZYQT) on the human sperm motility was evaluated using the more objective sperm motility assessment methods of transmembrane migration method (TMM) and computer-assisted semen analysis (CASA). TMM analyses indicated that while 'normal' sperms were not affected, 'abnormal' sperms were significantly stimulated by 1.0mg, 0.1mg and 0.001mg/ml of BZYQT. CASA yielded similar results. The TMM index (progressive sperms/total sperms in units) is closely correlated to male fertility. Using the sperm velocity (V) of 25 micros/second and straightness (S) of 80% as the progressive criteria, analysis with the Hamilton Thorn Research Analyser indicated 9 cases with original sperm progressive index of ＜40% were improved in vitro with 0.1mg and 0.01mg/ ml of BZYQT.