Diaziquone is an aziridinylbenzoquinone with properties suggestive of an alkylating agent. The drug has shown broad antitumor activity against numerous transplantable murine tumors including curative activity against several intracerebrally implanted tumors. Diaziquone is rapidly and extensively metabolized by the liver. Diaziquone is a potent marrow suppressive agent inducing significant degrees of leukopenia, granulocytopenia, and thrombocytopenia in humans. Thrombocytopenia is often severe. Diaziquone alkylates and cross-links DNA during all phases of the cell cycle, resulting in disruption of DNA function, cell cycle arrest, and apoptosis. This agent can also form free radicals, thereby initiating DNA damage via DNA strand breaks. Due to its lipophilicity, diaziquone readily crosses the blood brain barrier. In phase I and preliminary phase II trials, diaziquone has demonstrated activity against primary brain tumors. Little activity has been seen in other tumor categories.