In situ -gelling systems has the great potential in the wide areas of drug delivery. The application areas of such systems are broad and these systems can be formulated not only as gels but also as in situ gelling nanospheres, microspheres and liposomes. To overcome the drawbacks associated with conventional drug delivery systems and take advantages of both solutions and gels, such as accurate dosing, ease of administration of the former and longer precorneal residence of the latter, a newer concept of in situ gelling drug delivery systems was came in light for the first time in the early 1980s. In situ gelling systems are the polymeric solutions which can be administered in solution form and immediately undergoes sol-gel phase transition in to a viscoelastic gel upon exposure to physiological conditions (e.g. pH, temperature and ionic concentration) or application of external triggers. In situ gelling systems seems to have wide applications in ocular therapy. A lot of research is going on in this area proves the fact that in situ gelling systems can be advantageous in the ocular drug delivery. In the present review we will discuss recent researches involving application of in situ gelling polymers, their applications in the various domains of drug delivery and marketed formulations based on in situ gelling systems.