The quality factor Q has been measured in the Pacific Ocean along many paths using long period seismograms of the Geoscope and IDA networks. The Love and Rayleigh phase velocity and QR-1 have been regionalized in the period range 60 s to 200 s, and then simultaneously inverted at depth to obtain 3D images of S-wave velocity and attenuation Q&bgr;-1 in the depth range 60--300 km. Up to 100 s, three very attenuating zones appear, one under the East Pacific Rise (E.P.R), another one around Hawaii, a third one east of Kermadec. By inversion, those three anomalies are found stable down to 160 km. Below 200 km, lateral variations are less intense and differently distributed; the maximum attenuation seems to concentrate along a northeast trend in the North Central Pacific. ¿ American Geophysical Union 1993