Inverse gas chromatography (IGC) has been applied to observe the interactions in filled polymer-organic solvent as well as modified filler-polymer systems under conditions approaching infinite dilution of the volatile component. We investigated polyether-urethane-modified silica systems containing different kinds of modified silicas (filler) at 10% w/w loading. The fillers were modified with N-2-aminoethyl-3-aminopropyltrimethoxysilane (B2), 3-aminopropyltriethoxysilane (B3), 3-mercaptopropyl-trimethoxysilane (B4), n-octyltriethoxysilane (B5). The values of Flory-Huggins parameter chi(12)infinity calculated from the retention volumes indicate that interactions between filled polymer and solvent probe varied with type of the modifier and temperature. Authors propose to express the magnitude of modified filler-polymer interactions by Flory-Huggins chi(23)' parameter. The influence of conditions of IGC experiment (temperature, the type of filler, the nature of test solute) on the evaluated parameters is presented and discussed.