The luminosity function for contact binary stars of the W UMa-type is evaluated on the basis of the ASAS photometric project covering all stars south of \delta = +28 ^ { \circ } within a magnitude range 8 < V < 13 .
Lack of colour indices enforced a limitation to 3373 systems with P < 0.562 days ( i.e .
73 % of all systems with P < 1 day ) where a simplified M _ { V } ( \log P ) calibration could be used .
The spatial density relative to the main sequence FGK stars of 0.2 % , as established previously from the Hipparcos sample to V = 7.5 , is confirmed .
While the numbers of contact binaries in the ASAS survey are large and thus the statistical uncertainties small , derivation of the luminosity function required a correction for missed systems with small amplitudes and with orbital periods longer than 0.562 days ; the correction , by a factor of 3 \times , carries an uncertainty of about 30 % .