A three-component ultrasonic current meter has been used to obtain measurements of current flucutations in the frictional boundary layer under an ice cover in Robeson Channel, Northwest Territories, Canada, during July 1974. The Reynolds stress against the underside of the ice floe was computed by a time series analysis of the correlation between downflow and vertical fluctuations of current. The average water drag coefficient, referred to a depth of 1 m below the ice and based on six runs in which the mean current was in the range between 12 and 32 cm s-1, was 1.05¿10-3 with a probably error of ¿0.26¿10-3. Two runs, made at very low current, yielded much higher values of drag coefficient but are thought to be in error. Spectra of current velocity fluctuations, plotted as a function of frequency, approached the -5/3 slope predicted by the Kolmogoroff law. Cospectra showed no contribution to the momentum flux at frequencies above 1 Hz.