Microspheres are free flowing particles ranging from 1-1000u. Microspheres are having wide applications in drug delivery system. They are mainly used for targeted drug delivery of anti-cancer agents, ophthalmic agent and can be used for diagnosis purpose. In this article detail discussion was made on the polymers, preparation methods and applications of microspheres in pharmaceutical dosage form development. General methods of preparation are emulsion techniques, phase separation coacervation techniques, spray drying and spray congealing and solvent extraction, in-situ polymerization etc.  Advantages of microspheres use are targeted drug delivery, optimal therapeutic effects and minimum side effects. Recent trends are floating microspheres, radio immobilization using microspheres. Gastro-retentive floating microspheres are low-density systems that have sufficient buoyancy to float over gastric contents and remain in stomach for prolonged period. The drug is released slowly at desired rate resulting in increased gastric retention with reduced fluctuations in plasma drug concentration.