Spermatozoal morphology in semen from 114 fertile men, 107 infertile men with varicocele and 35 infertile men with infection of the accessory genital organs, aged from 18 to 53 years were evaluated by Papanicolaou-stained smears in order to investigate: (a) the frequency of abnormalities in the neck and tail of spermatozoa with an abnormal head and (b) the ability of prediction of the morphology of one sperm part when the morphology of another part is known. The investigation showed that: (1) morphological abnormalities in the neck are significantly higher (P < 0.001, P < 0.01), when the head was abnormal, compared to spermatozoa with a normal head in fertile men and in men with varicocele, respectively; (2) morphological abnormalities in the tail are also higher (0.05 < P < 0.1) in spermatozoa with an abnormal head in men with infection; (3) the proportional reduction of error (PRE) was low in all cases. Our results show that spermatozoa with abnormal heads more often present morphological abnormalities of their counterparts compared to spermatozoa with normal heads. Nevertheless, no prediction can be made on the nature of the morphology of a part of a spermatozoon on the basis of knowledge of its morphology of another part.