In-situ seismic attenuation was measured through the Upper Basalt Series using vertical seismic profile (VSP) data collected on Leg 104 of the Ocean Drilling Program's (ODP's) investigation of the Voring Plateau in the eastern Norwegian Sea. The Upper Basalt Series encountered at the site of the VSP experiment consist of 105 flows with interbedded volcaniclastics making up less than 10% of the section. The flows are of tholeiitic composition and vary in texture from massive fine-grained to vesicular medium-grained (Eldholm et al., 1987). Assuming a constant Q model, measurements were made using the spectral ratio method over the bandwidth 4-47 Hz. An effective spatial attenuation of 1.6 X 10 (super -4) dB.s/m+ or -0.5 X 10 (super -4) (Q = 40) was measured over a 660 m interval. The large error in our estimate is due to interference effects caused by large impedance contrast throughout the section. The contribution of scattering was computed using synthetic VSP data generated from a model of the impedance structure with no intrinsic attenuation. Scattering accounts for practically all of the observed attenuation. Within our range of error, intrinsic attenuation in the Upper Basalt Series is less than 0.7 X 10 (super -4) dB.s/m (Q > 100).