Oral modified-release multiple-unit dosage forms have always been more effective therapeutic alternative to conventional or immediate release single-unit dosage forms. With regards to the final dosage form, the multiparticulates are usually formulated into microspheres and filling them into hard gelatin capsules. Microspheres have received much attention not only for prolonged release, but also for targeting of drugs. In the current scenario, targeted drug delivery requires an efficient drug carrier which can deliver the drug specifically on the site of action in a sustained and controlled manner. Among many such carriers, microspheres fulfil all the parameters for a potent drug carrier. Microspheres are one of the multiparticulate delivery system which is prepared to obtain prolonged or controlled drug delivery. Microspheres are defined as free flowing powders of spherical shape, consisting of proteins or synthetic polymers, which are either biodegradable or nonbiodegradable in nature and ideally having a particle size ranging from 1–1000 μm. The variety of methods for the production of microspheres offers numerous opportunities to control the aspects of administration of the API. The current aim of this review is to study various aspects of the microparticulates drug delivery system including types of microsphere drug delivery system, method of formulation, evaluation & characterization of microspheres.