Chlamydia trachomatis was encountered in four cases during the evaluation of 29 premenarchal girls with gynecologic complaints during 1983. Only one of the patients had antecedent infection with Neisseria gonorrhoeae. The importance of using specific tests to actively establish a definite diagnosis of chlamydia is stressed. The susceptibility of the thin premenarchal vaginal mucosa to chlamydial infection is discussed as is the role of chlamydia as a marker for sexual abuse. Once a diagnosis of chlamydial rectogenital infection is established in a child, it is mandatory to investigate for child abuse and sexual molestation as the source of the infection.