Poly(epsilon-caprolactone) was found to form inclusion complexes with alpha-cyclodextrin to give crystalline compounds. The complexes are stoichiometric one-to-one (cyclodextrin:monomer unit) compounds. The yields of the complexes decreased with increasing the molecular weight of the polymer. They were characterized by IR, H-1 NMR, C-13 CP/MAS NMR, and X-ray diffraction. The inclusion modes are discussed.