The purpose of this study was to determine the frequency of chromosomal or genetic causes of primary amenorrhea, and was made to assess the etiology of disorders in those patients whose chromosome appeared normal. Sixty eight patients with primary amenorrhea were evaluated clinically and cytogenetically, which were refered to our Cytogenetic Laboratory in Department of Obstetrics and Gynecology, Pusan National University Hospital, from Aug. 1988 to Dec. 1996. The results were as follows. l. Out of 68 cases with primary amenorrhea, 40 cases (58.9%) had the normal chromosome constitutions and 28 cases (41.1%) had the abnormal chromosome constitutions including 46, XY. 2. Turner's syndrome was found in 25 cases (36.7%), consisting of 11 cases (16.1%) of 45,X, 3 cases (4.3%) of 46,X,i (Xq), 1 case (1.5%) of 46,X, inv (X), 1 case (1.5%) of 46,X, del (Xq), 1 case (1.5%) of 46,X, del (Xp), 1 case (1.5%) of 46,X, tel (Xq), 1 case (1.5%) of 45,X/46,XX, 1 case (1.5%) of 45,X/46,XY, 1 case (1.5%) of 45, X/47,XXX, 2 cases (2.9%) of 45,X/46,X, del (Xq), I case (1.5%) of 45,X/46,X, del (Xq), 1 case (1.5%) of 45,X/46,X, r (X). 3. 3 cases (4.3%) had the 46,XY chromosome constitution consisting of 2 cases (2.9%) of testicular feminization syndrome and 1 case (1.5%) of pure gonadal dysgenesis. 4. Among 40 patients whose chromosome are normal, the etiologies of amenorrhea were assumed to be caused by 11 cases (27.5%) of hypogonadotropic hypogonadism (idiopathic), 10 cases (25.0%) of congenital absence of vagina, 5 cases (12.5%) of pure gonadal dysgenesis in order of frequency.