During 19 nights in the period from the end of November 1985 until mid-march 1986, measurements of the sodium layer were performed with a lidar system located at Andoya (69¿N, 16¿E). Under these conditions we find the following average properties of the sodium layer: a Na column density of 5.6¿109 cm-2, a Na density of 6100 cm-3 at the layer peak, an altitude of 89.2 km for the layer peak and a layer width (FWHM) of 9.0 km. At Andoya no significant seasonal trend in the Na layer parameters is apparent during the winter period. These results are compared with those obtained at several different latitudes by other researchers. We present the mean sodium density profile for the winter period over Andoya and the Na number density scale height distributions. A statistical analysis reveals averages of --0.4 sodium density scale height at the layer bottom and 2.5 km at 100 km altitude, the latter continuously decreasing with increasing altitude. From the mean Na scale heights obtained for altitudes below 90 km we can derive that in the range from 80 to about 86 km the density of sodium grows almost quadratically with altitude. From the mean Na scale heights obtained for altitudes above 95 km altitude, vertical effy cofficients and the vertical Na flux can be calculated. ¿ American Geophysical Union 1988