We study the morphology of asymmetric A(8)B(48)A(8) triblock copolymer thin films confined between two homogeneous surfaces (walls). Morphology is investigated as a function of the film thickness and the strength of the wall-polymer interaction. For very thin films we observe cylinders perpendicular to the walls for a wide range of wall-polymer interaction. With increasing film thickness other morphologies are becoming more stable. We observe wetting layers of short, end blocks, cylinders parallel to the walls, and perforated lamellae. For thick films perpendicular cylinders remain stable only for a very narrow range of wall-polymer interaction. (C) 2003 American Institute of Physics.