In this paper we consider the problem of deformation quantization of the al
gebra of polynomial functions on coadjoint orbits of semisimple Lie groups.
The deformation of an orbit is realized by taking the quotient of the univ
ersal enveloping algebra of the Lie algebra of the given Lie group, by a su
itable ideal. A comparison with geometric quantization in the case of SU(2)
is done, where both methods agree.