Study of sperm motility is associated to the development of precise and economical systems of evaluation. The purpose of this work was to develop an Objective Semi-Automated Method (MOSA) to evaluate the sperm motility. Human semen samples were registered by video-microscopy. The same videofilms were analysed with the MOSA, the subjective method and the automated CellSoft method. The percentages of motile and immotile sperms were equivalent with the three methods. The percentages of rapidly and slowly motile sperms were similar both with the MOSA and the subjective method. The curvilinear and linear velocities as well as the linearity values obtained with the MOSA were different to those obtained with the CellSoft, although such differences would be biologically acceptable. MOSA is an inexpensive, objective and precise method that does not require trained technicians and allows evaluation of several parameters of sperm motility.