We calculate photon production from a quark-gluon plasma which is anisotropic in momentum space including the Compton scattering, q((q) over bar )g -> q((q) over bar)gamma, and annihilation, q (q) over bar -> g gamma, processes. We show that for a quark-gluon plasma which has an oblate momentum-space anisotropy, < p(L)(2)><< p(T)(2)>, the photon production rate has an angular dependence which is peaked transverse to the beam line. We propose to use the angular dependence of high-energy medium photon production to experimentally determine the degree of momentum-space isotropy of a quark-gluon plasma produced in relativistic heavy-ion collisions.