Results of a 1981 study are complemented and analyzed with respect to epididymal histology in 94 patients undergoing uni- or bilateral epididymo-deferential anastomosis. Testicular histology was normal in all patients. Epididymal histology could be differentiated into two main groups: one with normal or only slightly altered epididymis, the other with major epididymal lesions. Repermeabilization was more frequent and of better quality (10 X 10(6) sperm/ml or more) in the first group, in which there were also all the pregnancies. Previous genital infection or injury is of poor prognosis due to the severe epididymal lesions present.