Abstract: A method and an apparatus for determining in a radar system the optimum eination threshold for suppressing permanent echoes are described. A basic elimination threshold is defined which is modified once per revolution of the radar antenna or several times during each revolution in each area covered by the radar system, by the addition or the subtraction of a coefficient depending on the comparison of the amplitude of the video signals with a previously set threshold. Then the residual clutter rate is calculated for each revolution of the antenna and also for each area covered and is compared with two fixed values, i.e. an upper and lower limit. A coefficient is derived from this comparison and is added to or subtracted from this previously set normal threshold, depending on whether the result of the comparison, is less than the minimum-rate value or greater than the maximum-rate value.