||Theranostic nanomedicines for simultaneous diagnosis and therapy of various diseases have received a great deal of attention. In this presentation, I am going to introduce hyaluronic acid-based theranostic nanomedicines, which have been recently developed in my lab. Hyaluronic acid (HA), an anionic glycosaminoglycan with repeating carboxylic acid groups, is abundant in humans, especially in the extracellular matrix. It could be served as polymeric backbone for bioconjugation, substrate for enzymatic and oxidative degradation, and mediator for pH-responsive drug delivery. Based on these properties of HA, we developed redox-, enzyme-, and pH-responsive theranostic nanoparticles for imaging and subsequent therapy of cancers and activated macrophages.