A fractal approach which takes into account the effect of surface heterogeneity brought about by ligand immobilization on surfaces on the binding and dissociation kinetics is presented here. The method provides us with an attractive and convenient alternative to model (a) analyte-receptor binding and (b) binding and dissociation kinetics for DNA biosensor applications. Examples analyzed include using a DNA molecular beacon biosensor and a plasmid DNA-(cationic polymer) interaction biosensor. The molecular beacon example provides some insights into the nature of the surface and how it influences the binding rate coefficients. The DNA-cationic polymer interaction example provides some quantitative results on the binding and dissociation rate coefficients. Data taken from the literature may be modeled, in the case of binding, using a single-fractal analysis or a dual-fractal analysis. The dual-fractal analysis results indicate a change in the binding mechanism as the reaction progresses on the surface. A single-fractal analysis is adequate to model the dissociation kinetics in the example presented. Relationships are presented for the binding rate coefficients as a function of their corresponding fractal dimension, Df, which is an indication of the degree of heterogeneity that exists on the surface. When analyte-receptor binding is involved, an increase in the heterogeneity on the surface (increase in Df ) leads to an increase in the binding rate coefficient. Keywords: DNA biosensors; binding and dissociation rate coefficients; fractal dimensions; heterogeneity