1- Results from the SMC experiment at CERN. 2- The COMPASS experiment at CERN

SMC : The SMC collaboration has measured the proton and deuteron spin structure function $g_{1}$ in the kinematic range $0.00006 < x < 0.8$ and $0.02 < Q^{2} < 100$ GeV$^{2}$. A brief summary of the NLO pQCD global analysis of all $g_{1}$ world data available in 1998 is given. The first moments of the proton, deuteron and neutron structure function were calculated in two factorization schemes ($\overline{MS}$ and AB). They lead to a value of $a_{0}$ close to 0.2, which corresponds to $\Delta\Sigma = 0.19$ in the $\overline{MS}$ scheme, and 0.38 in the AB one. The Bjorken sum rule is tested and found to agree with the theoretical predictions at the level of 10 %. \\\\COMPASS : The first goal of the COMPASS experiment at CERN is the measurement of the contribution of the gluon polarization $\Delta g$ to the nucleon spin. The measurement will be done by scattering high energy polarized muons on a polarized proton or deuteron target. The photon gluon fusion process, which is sensitive to the gluon density distribution, will be signed by the presence of charmed particles $(D^{0} , \bar{D^{0}})$ or of high $p_{t}$ hadron pairs of opposite charge. In addition to $\Delta g$, the longitudinal and transversely polarized parton distributions will be measured for the different flavors. A new spectrometer with large acceptance, high rate capability and identification of particles is being commissioned.