The development of superabsorbent hydrogels (SHs) is a very important issue in both academic and industrial fields because of their applications in several technologies. The impressive number of publications dealing with SH confirms this statement: a quick search in the ISI (Web of Science) database under the words superabsorbent hydrogels revealed more than 600 articles published, with about 80% of those published in last decade. Current studies on the development of SHs have focused on the formulation of highly functional materials with enhanced properties for suitable applications in different fields. In light of this, the incorporation of microsized or nanosized materials in SH formulations has been explored as a very attractive strategy for tailoring desired properties. In this review, we discuss relevant aspects of the current knowledge of SHs and nanocomposite polymer hydrogels, mainly those based on chitin and cellulose nanocrystals (fibers and/or whiskers), bringing to light some structure–property relationships and future trends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39725.