The mechanism of charge carrier generation by X-rays in anthracene crystals has been studied. We conclude that charge carrier pairs are generated by electrons due to the scattering of X-rays and the separation mechanism is in disagreement with the Onsager model. Recombination of charge carriers determines the slope of the photocurrent-electric field characteristics. The experimental current-electric field characteristics have been described theoretically and the role of photoinjection of charge carriers by X-rays from metallic electrodes has been established.