The dynamics of Surface pressure (pi) of DNA adsorbed onto mixed monolayers of octadecylamine (ODA) with trans-diaquo-1,3-bis(salicylideneamino)propanechromium(III) perchlorate, [Cr(salprn)(H2O)(2)]ClO4, has been measured. The adsorption of DNA takes place only when a lower concentration limit of [Cr(salprn)(H2O)(2)]ClO4 is present in the spread film, indicating synergism due to the possible interaction of DNA with [Cr(salprn)(H2O)(2)]ClO4 after interacting with loosely or moderately packed ODA molecules through hydrogen bonds. The results point to an enhanced DNA adsorption by relatively dilute ODA monolayer densities and a decline of adsorption with dense lipid monolayer.