Photoluminescent Ru(bpy)(3)(2+) complex, electron-accepting methylviologen, and an amino acid residue model compound were dispersed in a polysiloxane film, and photoinduced electron transfer from the excited Ru(bpy)(3)(2+) to methylviologen and the effect of amino acid residue model on the electron-transfer distance have been studied. The electron-transfer reaction was analyzed by a static model, and the electron-transfer distance was calculated considering the distance distribution between the nearest neighboring molecules as well as their excluded volume effect. In the absence of the amino acid residue model, the electron-transfer distance was obtained to be 1.4 nm. p-Cresol, a model compound of tyrosine residue, did not affect the electron-transfer distance, but 3-methylindole, a model of tryptophan residue, increased the electron-transfer distance to twice (2.7 nm) that without it.