This paper presents the estimates of frequency-dependent attenuation of S-waves for five different regions of the crust in the Sea of Marmara. The estimation method for the S-wave attenuation is based on the rate of decay of the S-wave to coda wave amplitude ratio with distance, Q(s)(-1). The epicentral distances of the selected earthquakes are between 15 and 70 km and the duration magnitudes are between 2.4 and 3.9. The quality factors, Q(s), are calculated at frequencies 1.5, 3, 6 and 12 Hz and a lapse time 50 s. The frequency dependency of average Q(s) values calculated at these frequencies for five regions is 40 +/- 5 f (1.03+/-0.06). The estimated Q(s) values for five regions ranging from 13+/-1 f(1.22+/-0.05) to 94 +/- 3 f(0.83+/-0.04) indicate the regional differences in the rheology and tectonic activity of the crust. (C) 2004 Elsevier B.V. All rights reserved.