A fundamental process in all organisms is their ability to regulate gene expression in response to developmental and environmental signals. In Chlamydia, changes in gene expression are closely linked to the presence or to undetectability of eukaryotic-like histones observed late in the parasites life cycle. It is becoming increasingly clear that these histone-like proteins are involved in macromolecular confirmation of DNA. However, their functional role(s) in chlamydial development and the underlying mechanism(s) involved in their degradation and dissociation are largely unknown. It is not surprising therefore that eukaryotic-like histones are a focus of intense research in several laboratories around the world. Recent studies on the interaction of eukaryotic- like histones with DNA, the role of phosphorylation and identification of a histone specific protease are beginning to unravel the mechanism of stage specific differentiation and gene expression in Chlamydia. In this article we review recent advances on the eukaryotic-like histones that have set the stage for elucidation of the chlamydial developmental cycle.