New naphthalimidopropyl, bisphthalimidopropyl and bisnaphthalimidopropyl (BNIP) derivatives were synthesised and characterised. Their interactions with Calf Thymus DNA were studied by UV spectrophotometric analysis and a competitive Ethidium bromide displacement assay. Cytotoxicity was determined by MTT assay in a breast cell system (MDA-MB-231 and MCF-10A cells). All BNIPs exhibited strong DNA-binding properties and cytotoxic activity with IC(50) values in the range of 0.83-12.68 microM (24 and 48 h treatment). In addition, the uptake of BNIP derivatives within cancer cells was not via utilisation of the MGBG polyamine transporter. Put together the results confirm that the presence of the bisnaphthalimidopropyl and alkyl linker functionality are crucial for exerting DNA-binding and cytotoxic properties, hence demonstrating promise in their further development as potential anti cancer agents.