In view of contradicting opinions regarding the chances by operations of unilateral congenital cataracts, we tested 97 children systematically since 1966. We especially tried to find out which functional meaning can be given to the operation and the following occlusion treatment. 64 children were operated, of these 22 in their 1. and 2. year of life, and an attempt of occlusion therapy followed. By 31 children test results were insufficient due mainly to the lack of cooperation of the parents who did not completely carry out the recommended therapy. In 2 patients the visual acuity improved clearly with central fixation. 6 children had a subjective, reliable orientation although their visual acuity lied under 0,2 and no central fixation was achieved. By the visual acuity and fixation test, they did not however differenciate from other children, who showed no improvement subjectively. The occlusion therapy was broken up by 15 children because of subjective discouragement and no signs of progression concerning the therapy. In retrospect serious operative complications within the observation time were not noted. Every type of cataract requires individual surgical techniques. Obviously, in such cases the measured visual acuity is not the appropriate criteria to judge the functional performance of the eye.