The form of the active drug administered to patients is important as far as effectiveness of the disease therapy is concerned. From this point of view modifications of medicinal substances are searched for that the obtained compounds have the best physicochemical and pharmacodynamic properties. Pharmaceutical companies allocate significant funds for this type of research. The key property that needs to be improved is the solubility of biologically active substances. This is related to the fact that over 40% of drugs available on the pharmaceutical market are characterized by low solubility in water.Thus, the paper describes the most important strategies used in the poorly soluble drug delivery systems, e.g. physical and chemical modifications, formulation based, modification of partition coefficient and lipid systems. The authors discussed various techniques used to enhance solubility of poorly water soluble drugs with their advantages and limitations.