Pelvimentry by Colcher-Sussman method was performed in 130 primigravida at Eul Ji hospital during the period of February 1977 to September 1980. They were divided by mode of delivery retrospectively in 2 groups---A group was 99 cases who had vaginal delivery, and B group was 31 cases who have been delivered by delivered by cesarean section. The comparison was made between 2 groups by ANOVA test and x2-test. The results were as followings. I. The measurements of X-ray pelvimetry for 2 groups. (cm) A group B group 1. Pelvic inlet A-P diameter; 12.80$pm$0.95 12.07$pm$0.95 Transverse diameter; 13.14$pm$0.66 12.58$pm$0.69 Mean diameter; 12.97$pm$0.55 12.33$pm$0.62 2. Mid-pelvis A-P diameter; 12.29$pm$0.86 11.62$pm$0.88 Transverse diameter; 10.18$pm$0.74 9.75$pm$0.76 Mean diameter; 11.23$pm$0.55 10.69$pm$0.57 3. Pelvic outlet A-P diameter; 7.76$pm$1.07 7.68$pm$1.18 Transverse diameter; 10.19$pm$0.79 9.43$pm$0.80 Mean diameter; 8.94$pm$0.73 8.60$pm$0.68 4. Fetal head Average diameter; 10.43$pm$0.38 10.64$pm$0.40 All the measurements described above except for the A-P diameter of the pelvic outlet were significant between 2 groups by ANOVA test (p<0.05) II. The comparison of other fetal and maternal factors between 2 groups. 1. Engagement of fetal head. Absence of engagement of fetal head were 5.1% in A group, and 25.8% in B group. The significance was noted between 2 groups by x2-test(p<0.05) 2. Type of coccyx. Slightly anteriorly deviated coccyx were 20.2% in A group, and 29.0% in B group. There was not a single case in A group with markedly anteriorly deviated coccyx, and it was significant when compared the 2 groups by x2-test(p<0.05) 3. Type of sacrum. Flat sacrum was not seen in A group, but 12.9% in B group, and there was significance between 2 groups by x2-test(p<0.05) 4. Position of fetal spine, Sex of fetus, presentation of fetal head, and body weight of fetus were not significant between 2 groups by x2-test.