Seminal fluid from 170 men was examined for acrosomal abnormalities of sperm (Papanicolaou procedure X 1000) and for y-positive cells (quinacrine-stained smears). No correlation was found between these parameters, suggesting that acrosomal abnormalities are similarly distributed among x- and y-bearing spermatozoa. The proportion of y-positive sperm was found to be low (23.6 + 10.7% (SD) for the oligozoospermic specimens and 23.7 +/- 9.8% for specimens with sperm counts above 40 million/ml). Three degrees of fluorescence intensity were observed--weak, moderate, and strong--the strong fluorescence being associated with the highest percentage of y-bodies (30.6 +/- 12.7%, 36.6 +/- 5.7%) and the weak fluorescence with the lowest (16.7 +/- 7.0%, 15.0 +/- 9.5%). It is suggested that structural abnormalities and/or metabolic alterations in either the DNA molecule or the chromosomal proteins may be responsible for variability in the ability to bind quinacrine compounds.