The synthesis of actinomine, a model compound for the investigation of the actinomycin-DNA interaction is discribed. In place of the pentapeptide lactone rings, actinomin has N,N-diethyl-ethylenediamine groups; it binds to DNA as strongly as actinomycin C1 (D) does. Additional replacement of the 4,6 methyl groups of the chromophore by tert-butyl residues strongly reduces the binding of actinomine to DNA. This result is consistent with intercalation of the actinomine chromophore between the DNA base-pairs, a reaction that is sterically blocked by the tert-butyl groups.