Unexplained infertility is still one of the most important problems in infertility management. As the incidence of unexplained infertility is ranging 0%-37% of infertile couples, it is must be investigated to be explained. Failed ovum pick up should be considered one of important causes of unexplained infertility. Ovarian ligament was studied in an attempt to answer the question of the question of the ovarian ligament may affect on the mechanism of ovum picking. So we study the ovarian ligament histopathologically and its length was measured. The mean length of Ovarian ligament in the fertile cases was 2.3080 cm and in the cases of unexplained infertility was 2.6730 cm that means that ovarian ligament is longer in cases of unexplained infertility nearly about 0.265 cm than in the fertile cases. The histopathological analysis of the ovarian ligament in the fertile cases: the percentage of fibrous to muscular component of the ligament 5%-10 % of total content of the ligament .the ovarian and uterine attachment characterized by presence of a sort of erectile tissue manifested as vascular plexus extending in the ligament 3-5mm distance, in nearly 65% of ligaments there is area of hyaline degeneration with colloidal like material extending for nearly 0.5 to 1.5 cm.