Thirty-one patients with advanced solid tumors who either failed to respond to chemotherapy and radiation or who showed insignificant responses were given melatonin at 10mg/day orally for 3 months. After the study period, none of the patients developed adverse reactions to melatonin or had discontinued treatment. Thirty-nine percent demonstrated disease stabilization with no further growth of either the primary tumor or that of secondary tumors. The patients experienced improvement in their general well-being and showed decreased levels of IL-6.