Chlamydia trachomatis is a bacterium that can only replicate in human cells and is recognized as an infectious agent of sexual and perinatal transmission. The objective of this research is to Investigate antibodies of the IgM and IgG classes against C. trachomatis in the serum of patients of both genders with clinical suspicion of Chlamydia infection in the population of the city of Queimados, Baixada Fluminense region, Province of Rio de Janeiro, Brazil. Antibody detection was performed in the serum of 55 patients of both genders. The kits used for diagnostics were: Chlamydia trachomatis IgG ELISA antigen purified reactive MOMP antigen, serotype K for IgG and C. trachomatis kit (IgM) ELISA method for IgM. Total incidence rate was determined in 51%, being more frequent among women. There was no significant association between C. trachomatis infection and the age of the patients. It is recommended to perform routine tests for the laboratory diagnosis of this pathogen in order to avoid the evolution to more worrying health conditions