The conformational properties of an AB diblock copolymer chain with different kinds of interactions between the units are studied by off-lattice Monte Carlo simulation. Using the Pivot algorithm, we calculate the radii of gyration, the end-to-end square distances of the individual blocks and of the whole molecule, the distance between the two centers of masses, and other static properties for various molecular weights and different solvent conditions. From these results, we obtain the dimensionless ratios that describe the effects of the AB heterocontacts relative to the precursor homopolymers. These quantities are compared with previous theoretical predictions.