Microgels/nanogels are crosslinked polymeric particles, which can be considered as hydrogels if they are composed of water soluble/swellable polymer chains. These polymeric particles possess high water content, biocompatibility, and desirable mechanical properties. Offers unique advantages for polymer-based drug delivery systems (DDS) such as a tunable size from nanometers to micrometers, a large surface area for multivalent bioconjugation, and an interior network for the incorporation of biomolecules. This review article describes the recent developments of microgel/nanogel particles as drug delivery carriers for biological and biomedical applications and also various synthetic strategies for the preparation of microgels/nanogels.