RESUMEN
In this overview is observed the history and presence of Chlamydia infections, which accompanied the human in its evolution. As a sexually transmitted disease it affects the fertile age. The unique life-cycle of this intra-cellular microorganism is reason for the difficulties of its identification in the past. The technological development in immunology and microbiology field, in present days made possible its isolation, antigen analysis and antibodies identification in the infected person and as well as serology typification. This allows to diagnose and treat in due time and secondary prophylaxis as well. There is no perfect laboratory test. Humans do not possess natural immunity against Chlamydia and at the same time the infection does not lead to durable immunity.