Chain molecules with both ends strongly adsorbed to a surface are discussed as a model system for adsorption of triblock copolymers. Irreversible adsorption and absence of interaction between chain monomers and surface are assumed. Monte Carlo calculations are used to investigate the average conformation and the probability of knot formation for separate coils. A comparison is made with the probability of knot formation in ring polymers and scaling predictions. For overlapping coils scaling predicts that the layer thickness depends on the preparative stage due to the requirement of conservation of topological state, which leads to an additional excluded volume effect. © 1987, American Chemical Society. All rights reserved.