An extension of the singlet-level equations for the density profile to the case of adsorption of polydisperse fluids on solid surfaces is presented. Explicit calculations and comparisons with canonical ensemble Monte Carlo data have been performed for a polydisperse hard sphere fluid in contact with a hard wall by using the Percus-Yevick, hypernetted chain, and a modified Verlet approximation. A numerical solution of the density profile equations makes use of the orthonormal polynomials with the weight function corresponding to the distribution function of the diameters of fluid particles.