In April and May 1991 all women requesting abortion in Norway were screened for Chlamydia trachomatis and Neisseria gonorrhoeae. During the study period 2,194 abortions were carried out. The study included 2,110 women with representative tests for C trachomatis from the cervix uteri. Only 1,702 women were tested for N gonorrhoeae. The prevalence of N gonorrhoeae was 0.5% (8:1,702), and of C trachomatis 5.4% (113:2,100). The prevalence of C trachomatis decreased from 9.1% among women less than or equal to 19 years to 2.0% among women greater than or equal to 35 years of age. Prevalence of C trachomatis was significantly lower among subjects resident in health region no. IV (mid-western part of Norway) than among candidates for abortion from the other four health regions. Being less than 25 years of age was the best single parameter for identifying chlamydia-positive cases. The prevalence of N gonorrhoeae among women seeking abortion in Norway is so low that screening is not recommended. However, the prevalence of C trachomatis is still high enough to recommend screening of all women less than 25 years of age who request abortion. Chlamydia-positive cases should be tested for N gonorrhoeae.