The ground cover ratio of a partial covering early winter wheal crop at the 1 cm stem + spike stage has been evaluated using a three channels CIMEL radiometer which simulated the SPOT satellite observation bands. During short periods guaranteeing constant illumination, the reflectance of experimental plots was linearly correlated to the plants' ground cover ratio within a range of 0 and 57 per cent. This result was used to construct charts to allow the estimation of the ground cover ratio of a given area from reflectance measurements in the red and infrared bands.