Monolayers of anionic amphiphiles, arachidic acid (C19COOH) and a double long chain sulfonic acid derivative (2C(12)SO(3)Na), were spread on the water subphase containing an ammonium-containing polysilane (APS), and Langmuir-Blodgett (LB) films from these polyion complex monolayers were prepared. Single layer deposition of these polyion complex monolayers was successfully achieved onto a hydrophilic substrate under all conditions examined, but multilayers could be prepared under limited conditions in the Z-type mode. The UV absorption spectra of the transferred C19COO(H)/APS monolayers indicated that the conformational state of APS in the films are dependent on the subphase pH. The absorbance of the transferred LB films confirmed that the APS is incorporated monomolecularly on the lifting process. Polarized UV absorption spectra revealed no preferential orientation of the APS backbone in the LB films. The multilayers formed in the Z-type deposition were eventually inverted to stacked bilayer structure (Y-type layers) after aging and successive annealing, as proven by the small angle X-ray reflectometry. LB films composed of 2C(12)SO(3)(-)/APS possessed a more refined layer structure with a more smooth surface than those of C19COO(H)/APS, probably due to a better dimensional matching of the APS unit and the cross section of the amphiphile. Finally, structural features of the C19COO(H)/APS polyion complex LB film were discussed in comparison with those of a homologous amphiphilic material reported previously (Seki et al. Macromolecules 1995, 28, 5609).