The problem of discharge of a supersonic axisymmetric jet from a nozzle at a jet pressure less than the pressure in the surrounding medium is considered. A calculation method is presented with account for the subsonic flow downstream of the central shock which forms near the axis of symmetry. Comparison of the results of the computation on a digital computer with the experimental data show the effectiveness of this method for determining the structure of the initial section of such an axisymmetric jet.