We examined the number of Chlamydia trachomatis inclusions produced in the initial passage of cell cultures of endocervical specimens from 1,231 women with positive chlamydial cultures who attended a sexually transmitted diseases clinic. Youth, white race, oral contraceptive use, and concurrent infection by Neisseria gonorrhoeae were associated with high chlamydial inclusion counts. Youth, white race, and oral contraceptive use were independent determinants of a high chlamydial inclusion count in women without concurrent gonorrhea but not in women with gonorrhea. Results of our study suggest that the degree of chlamydial excretion from the infected cervix may be influenced by characteristics of the patient being tested and may affect the ability to detect C. trachomatis in different patient groups.