Abstract Traditional Chinese medicine (TCM) has been used for centuries to treat and prevent certain ailments and diseases. Although TCM has served as mainstream medical care throughout Asia for many generations, it is considered an alternative medical system in much of the Western world. Because many TCMs are used primarily for cardiovascular indications characterized by a nitric oxide (NO) insufficiency, we hypothesized that some, if not all, of these TCMs have a robust NO bioactivity that may act to restore NO homeostasis. We tested a group of convenience samples of TCMs obtained in the United States for endogenous nitrite, nitrate, nitroso, and nitrite reductase activity as well as their ability to relax isolated aortic rings. The results from this study reveal that all of the TCMs tested reveal NO bioactivity through their inherent nitrite and nitrate content and their ability to reduce nitrite to NO. Many of the TCM extracts contain a nitrite reductase activity greater by 1000 times that of biological tissues. Repletion of biological nitrite and nitrate by these extracts and providing a natural system for NO generation in both endothelium-dependent and -independent mechanisms may account for some of the therapeutic effects of TCMs.