Nanogels have attracted considerable attention as nanoscopic drug carriers, particularly for site-specific or time-controlled delivery of bioactive mediators. A high diversity of polymer systems and the simple modification of their physicochemical features have provided multipurpose forms of nanogel preparations. Nanogels have outstandingly high stability, drug loading ability, biologic consistence, good permeation capability and can be responsive to environmental stimuli. Great potential has been shown by nanogels in many fields including delivery of genes, chemotherapy drugs, diagnosis, targeting of specific organs and several others. This review focuses mainly on different types of nanogels, methods of preparation including methods of drug loading, different modes of biodegradation mechanisms as well as main mechanisms of drug release from nanogels. Recent applications of nanogels are also briefly discussed and exemplified.