To provide an alternative to presently available subjective ways of measuring sperm motility which often yield inconsistent data, we devised a method for determining sperm motile efficiency with it one can express objectively the amount of active sperm movement. Using a melangeur for counting white cell, semen is diluted 20-fold in normal saline solution. With the diluted semen on Thoma's hemocytometer, spermatozoa passing its small quarter line in one minute are counted, and the value is divided by the estimated number of spermatozoa per ml. The quotient is multiplied by 100 and expressed by %/min. This shows the active movement of a spermatozoon per minute. In the present study, we measured sperm motile efficiency in 162 male sterility patients, 64 cases showed values of 49%/min or less, with a mean of 20.3%/min, 46, between 50%/min and 99%/min, with a mean of 70.1%/min; and the remaining 52 over 100%/min, with a mean of 195.9%/min. Among these there were 10 cases of successful pregnancy with a mean sperm motile efficiency of 152.7%/min, and 69.0%/min at the lowest. Our new method requiring no special equipment can easily identify active sperm movement and is easily reproducible,