The authors report ten cases of structural anomalies involving the Y chromosome: five cases of a dicentric Y chromosome, one ring Y chromosome, one case of a Y isochromosome containing the long arms, one deletion of the long arms (Yq-), one case of an abnormally long Y chromosome (Yq+) and one Y-autosome translocation. Analysis of clinical and chromosomal correlations, especially with respect to sexual differentiation, led to discussing the role of the Y chromosome.