Poly(dimethylsilane)s form inclusion complexes with cyclodextrins in high selectivity to give crystalline compounds. beta-Cyclodextrin forms complexes with poly(dimethylsilane)s of low molecular weight only, gamma-cyclodextrin with poly(dimethylsilane)s of high molecular weight in high yield, and a-cyclodextrin does not form complexes with poly(dimethylsilane) at all. Complexes were isolated and characterized by spectroscopic methods and X-ray diffraction.