Department of Organic Chemistry, Indian Institute of Science, Bangalore-560 012 Manuscript received 17 August 1998 Four cationic acridine derivatives have been synthesized. The positively charged amine residue in one of these is connected directly on to the acridine nucleus and in three other acridines, the amines are connected via a 9-CH2 unit to acridine. We have investigated the binding of these acridines with mammalian DNA by absorption titration, UV- and induced-CD spectroscopy and competitive ethidium bromide displacement fluorescence assay. The effects on the DNA duplex denaturation melting temperatures upon binding of each one of these are also examined. The results obtained herein clearly show that the introduction of a -CH2 group in the immediate vicinity of the intercalation moiety introduces alterations in the DNA binding characteristics of the resulting acridines.