Global awareness of cancer is one of the largest causes of death in people of various ages and racial backgrounds has led to research and many clinical studies in an effort to limit the progression of this disease. Chemoprevention by dietary constituents has emerged as a novel approach to control cancer incidence. A variety of mushrooms have been used traditionally for the maintenance of health, and for prevention and treatment of diseases. This review highlights some of the recent works that express promising anti-tumor effects. Mushroom extracts may modulate the response of host immune system; in particular, various mushroom polysaccharides are likely to effect promotion and progression stages towards cancer. Other substances contained in mushrooms may be able to interfere with tumor initiation through a variety of mechanisms.