Diffusion of binary mixtures of nonionic dyes (C.I. Disperse Orange 3, C.I. Disperse Red 15, and 1,4-dihydroxyanthraquinone) into nylon 6 film was examined by film roll method. Apparent diffusion coefficients of dyes in the mixture dyeing together with in the single dyeing have been determined at 60, 70, 80, and 90$^{circ}C$. Cross-term diffusion coefficients were also calculated. Diffusion coefficients of dyes used in the mixture of chemically dissimilar (C.I. Disperse Orange 3 and C.I. Disperse Red 15) are unaltered in comparison with single dyeings, while diffusion coefficients of dyes used in a combination of similar structures (C.I. Disperse Red 15 and 1,4-dihydroxyanthrqquinone) are decreased. It is suggested that the latter effect is due to the interaction between dyes in the solution and a certain competition of two dyes with the polymer.