The term control release means the release of the molecules from any reservoir in very precise and constant amounts and following zero-order or near-to-zero-order release kinetics. This type of formulation and device has a huge market over the medical world. The basic foundation of sustained release drug delivery system enhances the biopharmaceutical and pharmacodynamics pharmacokinetic properties of a drug in such a way that its usefulness is exploited, side-effects are reduced, and cure of the disease is attained easily. The international controlled-release drug delivery technology market has been divided on the basis of technology, application, release mechanism, and geography. This chapter describes these topics: metered dose inhalers, transdermal and ocular patches, drug eluting stents, activation-modulated drug delivery systems, polymer coating systems microelectromechanical technology, implants, micro reservoir partition controlled drug delivery systems, hydrophilic polymer matrix systems, targeted delivery, enzyme activated device.