A search was conducted for the signatures of Birkeland currents in the Earth's magnetic tail, using observed values of Bx and By from large sets of spacecraft data. The data were binned by x and y for -10>xGSM>-35 and ‖yGSM‖≤20RE(≤30RE for xGSM≤-25RE) and in each bin their distribution in the (Bx,By) plane was fitted by least squares to a piecewise linear function. That gave average x-y distributions of the flaring angle between Bxy and the x direction, as well as that angle's variation across the thickness of the plasma sheet. Angles obtained in the central plasma sheet differed from those derived near the lobe boundary. That is the expected signature if earthward or tailward Birkeland current sheets are embedded in the plasma sheet, and from this difference we derived the dawn-dusk profiles of the tail Birkeland currents for several xGSM intervals. It was found that (1) the Birkeland currents have the sense of region 1 currents, when mapped to the ionosphere; (2) both the linear current density (kiloamperes/RE) and the net magnitude of the field-aligned currents decrease rapidly down the tail; (3) the total Birkeland current at x≈-10RE equals ≈500--700 kA, which is ~30% of the net region 1 current observed at ionospheric altitudes, in agreement with model mapping results; and (4) the Bz and By components of the interplanetary magnetic field influence the distribution of Birkeland currents in the tail. ¿ American Geophysical Union 1993