The structure of nonuniform three-component fluid mixtures is studied using a self-consistent density-functional approach as well as a simple weighted density approximation and also by computer simulation. The second-order direct correlation function and the bridge function of the corresponding uniform fluid mixture required as input in the self-consistent theory are obtained from integral equation theory using an accurate closure relation, whereas the available analytic expressions of second-order correlation function within the Percus-Yevick approximation is used in the simple weighted density approximation. This new approach is employed to predict the structure of ternary hard sphere fluid mixtures near a hard wall as well as the structure of ternary uniform hard sphere mixtures. The calculated density and concentration profiles of the nonuniform fluid mixtures as well as the radial distribution function profiles of the uniform fluid mixtures are shown to compare well with the computer simulation results performed in the present work. (C) 2003 American Institute of Physics.