We studied the effect of the hypogastric plexus preserving operation for Y-prosthesis replacement in abdominal aneurysm. The hypogastric plexus preserving operation was performed for avoiding postoperative sexual disorders such as the impotence and the abnormalities of ejaculation. With wide abrasion of retroperitoneum as usually, postoperative abnormalities of ejaculation occurred in 70% and postoperative impotence occurred in 50% of cases undergoing Y-prosthesis replacement. More reliable nerve preserving operation was the minimum abrasion of retroperitoneum and the aorta had not to he abrased at the origin of the inferior mesenteric artery, bifurcation of the aorta and the common iliac artery. Then with this nerve preserving operation, abnormalities of ejaculation occurred in 30% (p < 0.05) of cases and impotence occurred in 20% of cases. The results indicate that sexual dysfunction may he prevented to minimize by the nerve preserving operation.