During the one year period from February 1986 to January 1987, 839 pregnant women were screened for Chlamydia trachomatis infection of the uterine cervical canal by the enzyme immunoassay (EIA, Chlamydiazyme) method. Out of 768 normal pregnant women positive results were obtained in 21 women for a positive rate of 2.7%. In none of 64 women with spontaneous abortion or 7 women with stillbirth were positive results obtained. In 20 of EIA positive women labor was controlled. Extraordinary maternal abnormalities were not seen through labor and puerperium. Out of 21 babies born to these 20 pregnant women, chlamydial pneumonitis developed in 2 babies (10%) and chlamydial conjunctivitis in 1 baby (5%) and these babies were treated. Urethral samples were taken from 16 husbands of EIA positive women, and they were all EIA negative. As to the correlation between EIA and the culture method using HeLa 229 cells, the consistency rate was 78% (n = 18) for positive results and 100% (n = 66) for negative results. Chlamydial IgG antibodies were assayed in 19 out of 21 cases, and all of them yielded positive results. From these results, the importance of screening for Chlamydia trachomatis infection in our country was affirmed.