In summary, seventeen infertile men with varicocele in whom no other cause for infertility could be identified, were studied before and following varicocele repair. Morphologic alterations were the most common abnormality noted in the seminal fluid with all subjects demonstrating increased numbers of tapered or amorphous spermatozoa. Ligation of the varicocele resulted in improvement in one or more of the seminal fluid abnormalities in thirteen of the seventeen patients. Seven patients achieved a pregnancy. No single seminal fluid parameter was identified which was of predictive value in determining those subjects who would demonstrate improvement following varicocele repair.