Polymers are widely used in the delivery of drugs due to their superior properties and mass. They are used in the manufacture of drugs and in drug delivery devices. These drug delivery devices may be in the form of controlled drug delivery plants. The polymers used in colloidal drug delivery systems, consisting of small particles, show significant benefits in drug delivery systems due to improved drug loading and release properties. Polymeric nano particulate systems are available in many varieties and form chemicals. Non-toxic, decaying and biocompatible polymers are available. Some nano particulate polymeric systems have the ability to cross the blood-brain barrier. They provide protection from chemical damage. Smart polymers react to stimulus in the atmosphere as temperature changes; pressure, pH etc. therefore they are very beneficial in targeted drug delivery. Some polymeric systems combined with certain antibodies / biomarkers help in the targeting of specific molecules especially in cancer. More coated with thi-olated PEG, Silica-PEG improves water solubility and image stability. Rehabilitation of drug carriers e.g. PEG or dextran attachments to the lipid bilayer increase their blood circulation time. Polymer compounds such as Zoladex, Lupron Depot, On Caspar PEG intron are used to treat prostate cancer and lymphoblastic leukemia. Polymeric drug delivery systems are used for controlled drug delivery that ensures patient compliance.