Self-consistent field theory is used to investigate the density profile of diblock copolymer melts in a thin film confined between two surfaces, one of which carries a chemically active pattern. The temperature is slowly lowered through the critical point in order to obtain well organized structures. For strong surface interactions, the lamellae for symmetric diblock copolymers comply with the surface pattern. Their orientation depends on the ratio of natural bulk period L-0 to surface period L. For L(0)less than or equal to L, the lamellae tilt at an angle theta= arcsin L-0/L with respect to the surface, For L(0)greater than or equal to L, the diblocks are distorted close to the surface and the necessary relaxation off the surface induces parallel oriented lamellae with respect to the surface for films thicker than 2 lamellar periods. Very thin films still support the perpendicular orientation.