Between 1983 and 1985, 257 infertile men were examined for any present varicocele by means of the Doppler sonography, telethermography and palpation. Based on these findings, the spermiogram and the infertility history, high ligation of the spermatic vein was indicated in 89 patients with varicocele and a median duration of infertility of 36 months (6-88 months). Postoperative sperm examinations have shown a significant improvement in sperm count and morphology, but not in motility. The most significant drop was observed in germ cell concentration from 1.68 to 1.06 mio/ml (p less than 0.025 Wilcoxon signed rank sum test). The follow-up examination 6 years after the beginning of the study has shown that only 56 out of the 89 patients underwent surgery, whereas 33 patients refrained from it. Pregnancy rates were 42% (23 out of 55, 1 patient lost to follow-up) in the operated group and 45% (14 out of 31, 2 patients lost to follow-up) in the nonoperated group. The comparison of the two graphs showing pregnancy incidence clearly demonstrates that pregnancies in the nonoperated group occur earlier than in the operated group; it has to be noted, however, that several patients only refrained from being operated on because pregnancy had occurred before surgery was planned. On the one hand, our study confirms other authors' results, i.e. that pregnancy rates in the nonoperated group are relatively high despite present varicocele. On the other hand, the operated group achieved practically the same high pregnancy rate when monitored over a longer period of time.(ABSTRACT TRUNCATED AT 250 WORDS)