Modern stellar evolutionary tracks are used to calculate the evolution of a very large number of massive binary star systems (Mtot≳15M⊙) which cover a wide range of total masses, mass ratios, and starting preparations. Each binary is evolved accounting for mass and angular momentum loss (due to wind mass loss, mass loss during Roche lobe overflow of the primary, mass loss during a common envelope phase should it occur), through the supernova of the primary to the x‐ray binary phase. Using the observed rate of star formation in our galaxy and the properties of massive binaries, we calculated the expected high mass x‐ray binary (HMXRB) population in the Galaxy. We test various massive binary evolutionary scenarios by comparing the resulting predictions to the x‐ray observations. Our principle result is that approximately 70% of the overflow matter is lost from a massive binary system during mass transfer in the Roche lobe overflow phase. ©1994 American Institute of Physics.