Endocervical swabs from 212 women and urethral swabs from 100 men were tested by the routine methods for McCoy cell culture and simultaneously by a novel enzyme amplified immunoassay test to detect chlamydia antigen. Overall correlation of the amplified test with culture was 96.5%. The test proved to be a suitable screening procedure for genital chlamydial infection, particularly for large numbers of specimens or in cases in which culture was not available.