Aziridinyl substituted benzimidazolequinones are more toxic than methoxy analogues towards normal human fibroblast cells (GM00637). The aziridinyl substituent is required for hypersensitive killing of Fanconi anaemia (FA) cells (PD20i) deficient in FANCD2. Despite lacking quinone functionality, 4,7-dimethoxy-N-[(aziridin-2-yl)methyl]benzimidazole also induces hypersensitivity from FA cells, similar to their response towards mitomycin C. Expression of FANCD2 (in PD20:RV) corrects FA cell hypersensitivity supporting cellular response via the FANC pathway.