Vasal injuries during childhood and their effect on subsequent fertility. Thirty subfertile males had testicular obstruction following inguinal or pelvic surgery in childhood. All 13 patients with bilateral obstruction were azoospermic and 6 had developed antibodies to spermatozoa. Of 17 patients with unilateral obstruction, 11 had oligozoospermia and 6 had normal sperm counts: all had high titres of antibodies to spermatozoa (a significant difference from the men with bilateral obstruction). This indicates that male infertility can result from vasal or epididymal injuries in childhood due either to the obstruction itself or its immunological consequences. Following corrective surgery and prednisolone treatment for the antibodies, where appropriate, 5/17 patients with unilateral blocks and 1/11 with bilateral blocks successfully produced pregnancies. 