We describe a new type of desynapsis observed in the semen samples and/or testicular biopsies from four subfertile patients. The desynaptic anomaly affects one or more bivalents in each cell. The incidence of this meiotic anomaly in our series of subfertile males (925 meiotic studies by May 1981) is about 0.43%. The different types of oligochiasmatic meiotic mutation described in human subfertile males are classified according to our data and those published in the literature. © 1981 Springer-Verlag.