The shear wave velocity structure of the crust and upper mantle in Turkey was determined using single-station measurements of Rayleigh and Love wave group velocities in the 8-50 s period ranges. Group velocity dispersion data of fundamental mode constituted 19 paths for Western and 10 paths for Eastern Turkey. Dispersion curves are measured by applying the multiple filter technique to properly rotated three component digital seismograms. A differential inversion technique is applied to these group velocity dispersion data to determine the S-wave velocity structures of the crust and uppermost mantle. Our results show upper mantle S-wave velocities between 4.0-4.5 km/s, and a crustal thickness varying between 25-40 km from Western to Eastern Turkey.