Wetting in systems with different dispersities of the solid and liquid phases and with different types of interfacial interaction was investigated. Studied were liq-uid metal-amorphous carbon and liquid metal-solid metal film-ionic crystal sys-tems in which the drop size and the thickness of film-substrates varied in the range 3x10^5–2x10^2 nm, respectively. It was found that for systems of the metal-amorphous carbon type a reduction in particle size and in thickness of carbon films brings about a size effect during wetting as a consequence of a decrease in the surface energy of the corresponding dispersed phase. For metal-metal-ionic crystal systems, a size effect during wetting is also observed but it is mainly caused by a changed nature of the interfacial interaction in the dispersed phases. Some parameters derived from the experimental data determine the dependence of the surface energy of small particles on their size