As a remarkable class of nanomaterials, research on hydrogels is developing rapidly through the innovation and improvement of polymers, chemical synthesis and methods of preparation, formulations and fabrication process, as well as applications. This overview concerns the analysis of international patents on hydrogels through the global system for filing patent applications which is known as Patent Cooperation Treaty (PCT) and administered by Intellectual Property Organization (WIPO). More specifically, this study presents the state of the art by introducing what has been innovated and patented in relation to hydrogels. As results, a total of 11,757 patent applications related to hydrogels have been filled between 1979 and 2020. The United States leads the patent race in the hydrogel sector. Massachusetts Institute of Technology is one of the top innovators in the hydrogel-based research and development. Based on patent classifications, most patent applications are related to medicinal preparations characterised by special physical form and materials for prostheses or for coating prostheses including structure of prostheses use of preparations for artificial biological organs, as well as materials characterised by their function or physical properties, such as hydrogels or hydrocolloids.