  We discuss results of the $k_t$ - factorization approach for heavy
quark-heavy antiquark correlations in proton-proton and proton-antiproton
collisions for RHIC, Tevatron and LHC. We consider correlations in the
azimuthal angle as well as in the two-dimensional space of transverse momentum
of heavy quark and heavy antiquark. We compare results obtained with the help
of different unintegrated parton distributions (UPDF) from the literature.
