We present the results of hydrodynamical simulations of the circumstellar
medium around a Gamma-ray burst progenitor. We use the mass loss history of
a rapidly rotating, low metallicity massive star as input for our
simulations. The interior of this star is homogeneous due to rotational
mixing. In general, the mass loss rate of this star is low, while the wind
velocity is high, except when the star reaches critical rotation. During
these periods, the star produces adense, highly anisotropic wind, which radically changes the morphology of
the circumstellar medium. From our simulations we can predict the density
profile of the circumstellar medium along the polar axis of the star, which
is the medium into which the gamma-ray burst jet would expand. We can also
predict the likelihood of blue shifted absorption lines in the afterglow
spectrum.