Abstract The purpose of writing this review on pharmaceutical gel was to compile the recent literature with special focus on rational approach to topical formulation and basic components of topical drug delivery systems. Topical application of drugs offers potential advantages of delivering the drug directly to the site of action and acting for an extended period of time. Skin is one of the extensive and readily accessible organs on human body for topical administration and is main route of topical drug delivery system. Diclofenac when it is applied topically to the skin to ease muscular pains, sprains and strains. When diclofenac is applied to the skin as a gel (or a patch containing gel), instead of it having an effect on all of your body, it only works on the area that you have applied it to. Topical gels are intended for skin application or to certain mucosal surfaces for local action or percutaneous penetration of medicament or for their emollient or protective action.