This article examines how fungi have provided humanity with some of the most important medicines ever created, including penicillin, drugs that prevent organ rejection, and cholesterol-lowering statins. Many of these fungal compounds work as medicines because they target processes that are similar in both fungi and humans, helping them survive competition with other fungi while coincidentally treating human diseases. New researchers are now using modern genetic tools to discover additional fungal medicines, with several promising candidates currently being tested in clinical trials for cancer, depression, and other chronic diseases.