In this chapter, we present recent advances on the use of several different kinds of medicinal herbs to treat cancer, Parkinson’s disease (PD), heart disease, and depression. These include recent studies on the use of Vaccinium spp. (blueberries and relatives) for cancer treatment and prevention; blueberries in the diet to improve motor skills and cognitive ability in patients with PD; digitalis (foxglove) to treat patients with heart disease; and St. John’s wort that is used to treat patients with mild-to-moderate depression. The basic conclusion from these studies is that rigorous, well-designed clinical trials are needed to validate the safe use of these and other medicinal herbs for treatment of these and other diseases.