Analysis of the data from CELEBRATION 2000 experiment in southeastern Poland revealed azimuthal variation of the Vp velocity, unlikely to be caused by crustal inhomogeneity. This is explained by upper crustal seismic anisotropy and was analysed by the anisotropic delay-time inversion. The result, indicating 8--10% anisotropy, fits to the geology of the area, where tightly folded metapelitic rocks are abundant. The fast velocity axis direction of 115¿ (WNW-ESE) coincides well with the azimuths of outcropping folds axes and other deformational structures. In order to assess the credibility of the result, synthetic tests have been performed. The traveltimes calculated for isotropic models were inverted, to check if an artificial anisotropy will be generated. The tests indicate that realistic isotropic velocity inhomogeneities can only account for a fraction of observed traveltime variations, and that the anisotropy cannot be an artifact resulting from the inhomogeneous crust.