The endocannabinoids present a rich system of central cannabinoid (CB1), peripheral cannabinoid (CB2), and non-CB receptor-mediated pharmacology that has stimulated research in many fields including memory, weight loss and appetite, neurodegeneration, tumor surveillance, analgesia, and inflammation. HU-331 is a hydroxylquinone cannabidiol analog that exhibits potent antineoplastic activity on a variety of human cancer cell lines. It effectively inhibits the growth of human Raji and Jurkat lymphoma cells in vitro with an EC50 of approximately 0.2 &#181g/ml and an EC80 of 1.56 &#181g/ml. HU-331 also inhibits the growth of HT-29 colon carcinoma cells, which have been inoculated into nude mice, by more than 50% at a dose of 5 mg/kg.