  We present a mean-field theory of carrier-induced ferromagnetism in
Mn$_x$III$_{1-x}$V diluted magnetic semiconductors with a special emphasis
placed on the magnetic anisotropy. The valence band holes are described using
the six band Kohn-Luttinger model. We find that the magnetic anisotropy is a
complicated function of sample parameters such as hole density or strain.
Results of our numerical simulations are in agreement with magnetic anisotropy
measurements on samples with both compressive and tensile strains.
