Three kinds of quantitative indices, i.e. the degree of mixedness, an area-based criterion and the box-counting fractal dimension, have been investigated to find out their suitability for evaluating the degree of dispersion of single additives in compounded material. The Monte-Carlo technique is used to simulate various ideal and non-ideal cases of dispersion in single-additive systems. It has been found that the value of both the area-based criterion and box-counting fractal dimension are essentially independent of the particle size of the additive, so they are suitable quantitative indices for evaluating the degree of dispersion of single-additive systems. The investigation also shows how the fractal dimension can be used to characterize and interpret the degree of dispersion of a pigment in a polymer matrix obtained experimentally.