Two females with sperm antibody activity in their blood serum and cervical mucus were treated with high dosages of methylprednisolone. Both patients bacame pregnant during therapy. Following the birth of their f i s t offspring, one was treated with steroids and the other conceived without steroids in order to establish their second pregnancies. The sperm antibody activity showed a sharp decline in the blood serum and cervical mucus during therapy. The response of the females showed drastic modification in the antibody activity in that the females revealed a complete disappearance or a significant decrease in their initial sperm antibody reactions after treatment with high dosages of steroids.