Summary: Chlamydiae are intracellular bacterial parasites that develop and multiply within mucosal cells of humans and animals and amongst the most common sexually transmitted disease worldwide. If left untreated, infection with Chlamydia can lead to serious outcomes such as infertility, ectopic pregnancy and blinding trachoma due to tissue scarring. There are currently no vaccines available for these major diseases. Microbiological research on Chlamydia is advancing rapidly and recently mathematical models of the bacteria have been developed to assist understanding of the complex chlamydial developmental cycle. Here, we extend the current description of the chlamydial developmental cycle and review the models developed and their predictions about chlamydial pathogenesis. The computational techniques employed by these applications are outlined.