Nitrosoureas　are　significant　anticancer　alkylating　agents　and　generally　applied　for　the　clinical　treatment　of　a　variety　of　human　malignancies.　Nitrosoureas　undergo　decomposation　and　generate　active　electrophilic　intermediates　to　react　with　biological　macromolecules.　These　reactions　can　lead　to　DNA　alkylation　and　interstrand　cross-links　of　complementary　base　pairs,　which　finally　result　in　apoptosis　of　cancer　cells　so　as　to　exert　anticancer　activity　of　the　drugs.　Nitrosoureas　show　complicated　physiological　activity　in　animal　experiments　and　clinical　application.　Consequently,　the　mechanism　of　DNA　damage　induced　by　nitrosoureas　has　become　a　hot　issue　in　the　field　of　antineoplastic　drug　design　and　cancer　prevention.　In　this　paper,　the　studies　of　the　DNA　damage　mechanism　by　nitrosoureas　in　recent　years　are　reviewed.