Two large earthquakes (Ms=6.6, 6.9) occurred in 1985 near the North Nahanni River in the Northwest Territories, Canada, the first on October 5 and the second on December 23. The earthquakes were followed by long aftershock sequences. Aftershocks between M=1.0 and 3.9 were recorded by five to eight three-component stations during three field experiments in October 1985 and in January and September 1986. Two distinct shear waves were generally observed. In September 1986, the plane of polarization of the first arriving shear wave was well defined and averaged 156¿¿8¿ measured clockwise from north. The stress direction was inferred from the initial shear wave polarizations recorded at one station from a widespread aftershock distribution but was limited to no more than 10 km around it. The delay between first and second arriving shear waves was up to 190 ms. Assuming that the two shear waves result from anisotropy and that the entire ray paths, varying in length from 7 to 23 km, contributed, the maximum velocity anisotropy is 7%. However, the distribution of the anisotropy is not uniform. The pressure axes determined from fault plane solutions for the two main shocks are nearly E-W, normal to the compressive direction found in the September 1986 field survey from shear wave splitting data. Four out of seven of the aftershocks for which focal mechanism orientations could be determined showed pressure axis orientations that agreed with the stress direction inferred from the initial shear wave polarizations from the field survey. ¿ American Geophysical Union 1990