Abstract: Chlamydiae are prokaryotic, gram negative, intracellular parasites, causing a number of human diseases with serious sequelae. The exact mechanism of chlamydial attachment and entry into the host cell is still unclear. Chlamydia trachomatis, [SA.sub.2]F (L2) was tested for the activity of glycosidases. Glycosidases are involved in the synthesis and breakdown of cell-wall polysaccharides, and have a pivotal role in attachment to the surface of host cells as well as in the invasion process of other infective agents. For these reasons, glycosidases are likely to provide important information regarding the general behaviour of this bacterium. Ten different glycosides bound to p-nitrophenol (pNP) substrate were tested. Assays were performed on lysed and unlysed chlamydial extracts. Our results provided strong evidence for the existence of glycosidase activity in C.trachomatis, strain [SA.sub.2]F peaking at pH 5.0 and pH 7.5-8.0 There was a high enzymatic activity against p-NPa mannopyranoside and p-NP b-N acetylglucosamine with a recovery of 88% suggesting that the enzymes were present on the bacterial surface. Activity against these sugars, which form part of either the extracellular filler or in endoplasmic reticulum may suggest of a possible mechanism of cellular invasion.