Rabbits subjected three times a week for 7 months to administrations of fresh homologous semen, colonic enemas, or semen (previously frozen at -70 degrees) preceded by enema were monitored by a battery of biochemical and hematologic tests and histopathologic examination. No biochemical, hematologic or histopathologic changes were observed. Negative blood cultures and serum endotoxin determinations excluded any possibility of systemic bacterial infection caused or induced by the treatments. Wide temporary variations in the hematologic parameters, including concentrations of T and B cells, were observed in all treated groups. The relevance of these findings to immune status is not yet certain.