In May 1977, eddy flux measurements of momentum were made with a three-component ultrasonic current meter in the oceanic boundary layer under a first-year floe of fast sea ice in Barrow Strait. N.W.T. By using eddy correlation methods, values of horizontal Reynolds' stress were computed from each of 20 data runs of about 1-hour duration during which the mean current was reasonably steady. A least squares analysis in which water stress was assumed proportional to the square of the mean current yielded a value for the 1-m water drag coefficient 1.32¿10-3 with a standard deviation of 0.06¿10-3. The diameter of the floe was greater than 1 km and its mean thickness was 128 cm, with a standard deviation of 4 cm and a maximum deviation of 7 cm.