[en] As a first step toward a proper treatment of compact objects in binary systems the attraction force of two massive bodies connected by a rod is calculated in a post-Newtonian expansion. Contrary to a calculation by previous workers a start is made without specializing the internal structure of the bodies. General anisotropic pressures are considered and no axial symmetry for the bodies is required. The attraction force is considered in a post-Newtonian approximation. Newton's attraction force Msub(S1)Msub(S2)/R² plus terms of order 1/R³ and higher where Msub(S1), Msub(S2) are the Schwarzschild masses of the bodies is obtained. (author)