In order to determine polarized parton densities in nucleon we have made fits using all experimental data on spin asymmetries measured in the deep inelastic scattering on different nucleon targets. We have used in our analysis next to leading order QCD corrections in \overline {MS} renormalization scheme. The functional forms of polarized densities are based on the fit to unpolarized deep inelastic data made by the MRST group (MRST 99). We have concentrated on different models for gluon spin distributions. In the best fit we get for gluon polarization (at Q² = 1GeV²) \Delta G = -1.0 \pm 0.6. The obtained result does not depend very much on various model assumptions.

PACS numbers: 12.38.--t, 13.60.Hb, 13.88.+e, 14.20.Dh