Abstract: We report two unexpected findings ocurring after treatment of the antitumor drug mitomycin C with dithiols. The first finding relates to the reaction of mitomycin C with exactly one molar equivalent of dithiol to form a mitosene-like material with unusual physico-chemical properties. The second finding was the formation of unexpected dimeric mitosenes when the reaction of MC with dithiols was quenched at short reaction times. We hypothesize that both events are originated by an unprecedetended deaziridination reaction.