An alternative kinetic model of DNA melting curves, rising temperature kinetic evaluation, was recently suggested [Thermochim. Acta 284 (1996) 109] and applied to UV melting profiles of duplex DNA oligomers. We have investigated this kinetic model and compared it with the two-state thermodynamic equilibrium model. UV melting profiles for native DNA duplex oligomers were collected at various heating and cooling rates. Experimental melting curves of duplex DNA oligomers were found to be reversible and independent of the heating rates in range from 2.5 to 45 degreesC h(-1). When the melting curves were evaluated in the terms of the alternative kinetic model, specific kinetic rate constants for duplex denaturation depended on the heating rates. These results indicate that native DNA duplex oligomers exhibit equilibrium melting transitions and the suggested kinetic model is invalid for melting profiles of native DNA duplex oligomers collected at the studied range of heating rates.