The hygroscopic character of a pharmaceutical material is known to influence the behavior of the material during various stages of pharmaceutical process, manufacturing, packing, storage, and transport. It also influence greatly on the stability, appearance, efficiency of the materials. Hence it is important to classify and overcome the problems of the materials based on their hygroscopic nature. The following review covers the literature reports of classification, determination of hygroscopic materials based on their ability to absorb or adsorb water molecule from the environment. It also discuss about the effect of hygroscopicity due to uncontrolled humid conditions and basic methods to overcome the same.