Bilateral retroperitoneal lymphadenectomy is mainly a staging procedure in patients with stage I nonseminomatous testis cancer, and it causes permanent loss of antegrade ejaculation in approximately two-thirds of the cases. Between May 1978 and August 1981, 61 consecutive patients with no intraoperative evidence of lymph node involvement underwent unilateral retroperitoneal lymph-adenectomy for nonseminomatous germinal testis tumors. Microscopic metastases were found in 1 to 4 retroperitoneal nodes in 6 cases (9.8 per cent). Antegrade ejaculation was absent postoperatively in 11 patients (18 per cent), with no significant difference between patients who underwent lymph node dissection on the left or right side. Ejaculation returned spontaneously in 3 patients, 1 of whom fathered a child. The disease recurred in 10 patients 3 to 35 months after lymphadenectomy (median 6 months). Disease recurred in 8 of 55 patients (14.5 per cent) with negative nodes and 2 of 6 (33.3 per cent) with positive histological findings. No patient suffered retroperitoneal recurrence. The more than 3-year survival rates free of disease were 96.4 and 83.3 per cent in patients with pathological stages I and II disease, respectively. Unilateral retroperitoneal lymphadenectomy in patients with intraoperative stage I nonseminomatous germinal testis cancer preserves antegrade ejaculation in more than 80 per cent of the cases without apparently compromising the long-term survival.