On the basis of the most recent data, the fraction of known Wolf-Rayet binaries is 0.22. In the solar neighbourhood (d < 2.5 kpc) this fraction is 0.34
In order to assess the relative importance of massive binary evolution as one of the ways to produce WR stars, the galactic distribution of WR binaries is compared with that of single WR stars using improved intrinsic parameters and new data for the fainter WR stars.
In the galactic plane the increase of the binary frequency with galactocentric distance is confirmed.
In a direction perpendicular to the galactic plane it is demonstrated at all distances from the Sun that the single-line spectroscopic WR binaries with small mass functions have definitely larger |z|-distances than the ‘single’ WR stars and the WR binaries with massive companions. This is consistent with the evolutionary scenario for massive binaries summarized by van den Heuvel (1976). Among the ‘single’ WR stars the fraction of those with large |z|-distances is increasing with galactocentric distance, like the fraction of the known binaries. This implies that among the high-ļzļ ‘single’ WR stars as well as among the WR stars with lower |z|-values many binaries are still to be discovered.
The total WR binary frequency in the Galaxy could be well above 50 %.