Mushrooms are able to accumulate both primary and secondary metabolites. Medicinal and antioxidant properties of mushrooms are an excellent combination of their nutrition value. Recent studies have demonstrated that edible mushroom species contain non–hallucinogenic indole compounds and their derivatives. The indole skeleton is the basis of the substances serving important functions in the human body, such as serotonin and melatonin. These compounds fulfill the role of neurotransmitters or their precursors, exhibit antioxidant, anticancer, anti–aging actions, regulate the diurnal cycle in humans and participate in blood coagulation. These compounds and their derivatives are also anti–inflammatory and analgesic therapeutics.