SUMMARYWe analyze data from four GPS campaigns carried out between 1997 and 2002 on a network of 11 sites in the Suez-Sinai, the area of collision between the African and the Arabian plates. This is the key area to understand how and in which way Sinai behaves like a sub-plate of the African plate and the role played between seismic and geodetic (long term) deformation release.Our analysis shows that, on average, the Suez-Sinai area motion (in terms of ITRF00 velocities) matches African plate motion (NNR-NUVEL-1A model).However, the baseline length variations show transient deformations in Sinai and across the Gulf of Suez, reaching up a maximum value of about 1.5 cm in five years.Since current geodynamical models do not predict significant tectonic deformation in this area, we worked under the hypothesis that a contribute may be due to post-seismic relaxation. However, since the modelled post-seismic effect results modest and a certain amount of the detected deformation is not accounted for, we think that an improved modelling should take into account the lateral heterogeneities of crust and upper mantle structures.