  We investigate the sea quark polarization in the nucleon by means of a
combined next to leading order analysis to the recently enlarged set of
inclusive and semi-inclusive polarized deep inelastic scattering data. Using
the Lagrange multiplier method, we asses the uncertainty inherent to the
extraction of the different spin dependent parton densities in a QCD global
fit, and the impact of the increased set of semi-inclusive data now available.
We comment on future prospects at RHIC and JLAB and their potential impact in
the future determination of polarized parton densities.
