This study was done to explore the appropriate procedure of retroperitoneal lymph node dissection (RLND) to preserve ejaculatory function. The relation between postoperative ejaculatory function and area dissected at RLND was investigated in 47 patients with testicular cancer. The patients were divided into 5 groups according to the retroperitoneal area dissected. Group 1 (38 patients) underwent bilateral RLND, group 2 (3 patients) and 3 (2 patients) right unilateral RLND, and group 4 (2 patients) and 5 (2 patients) left unilateral RLND. The vertical limits of the dissected area were similar in all groups, namely renal pedicle and bifurcation of common iliac artery. The lateral limits were bilateral ureters in group 1, right border of aorta and right ureter in group 2, left border of aorta and left ureter in group 4, and vena cava and left ureter in group 5. Group 3 was similar to group 2, but the paraaortic region at the root of inferior mesenteric artery was also dissected. All patients in group 1 had dry ejaculation. Thirty patients in this group were examined for seminal emission and none of them could demonstrate seminal emission. Normal antegrade ejaculation was seen in group 2 and 4 patients, but retrograde ejaculation was recognized in group 3. Inability of seminal emission ws confirmed in group 5 patients. When consideration is given to the function of retroperitoneal sympathetic nerves, our results suggest that unilateral RLND without impairing superior hypogastric plexus should be adopted to preserve ejaculatory function.