The complex dichloro(N-ethylsalicylaldiminate) gold(III) [AuCl2(esal)] exhibits favorable cytotoxic properties toward a number of human tumor cell lines either sensitive or resistant to cisplatin. Crystallographic data show that the complex is a classical, slightly distorted square planar gold(III) complex with two chlorides and the bidentate salycilaldiminate moiety as ligands. The complex is sufficiently stable in DMSO or methanol but undergoes rapid hydrolysis in water or within a physiological buffer. The interaction of [AuCl2(esal)] with calf thymus DNA has been investigated through circular dichroism and analysis of the melting curves. Small but significant alterations of the CD spectra that are diagnostic of DNA binding are observed for r values greater than 0.02; in addition it is shown that [AuCl2(esal)] binding to DNA induces a slight increase of the melting temperature. On the ground of these results we conclude that DNA may represent a reasonable target for the cytotoxic action of this gold(III) complex, even if other mechanisms cannot be ruled out.