Thirty-four hypofertile male subjects with either oligospermia or azoospermia underwent infertility evaluation with assay of serum follicle-stimulating hormone, luteinizing hormone, testosterone and testicular biopsy. Cytogenetic analysis of testicular tissue and peripheral leukocytes was competed on 11 patients. Fifteen male subjects underwnet bilateral contrast vasography. These studies permitted segregation of the hypofertile male population from those with post-germinal hypofertility, primary germinal hypofertility or pre-germinal hypofertility. Retrospective analysis indicates that segregation of the hypofertile male population permits optimum selection for treatment intervention.