To the Editor.— "An Automated Mass Screening Program for Sickle Cell Disease" (218:1680, 1971) was of great interest to us because of our efforts in surveying a black population with a major impetus on genetic counseling. The authors are to be congratulated on their efforts toward increasing public awareness of the sickle cell problem, and we are in agreement with the need for using all the available communication media to accomplish this. We also agree with their recommendation that screening programs should have an educational emphasis and should involve the school population on a voluntary basis. However, for accurate genetic counseling the proposed automated screening technique is inadequate because it fails to detect hemoglobin C, known to be present in 2% to 3% of the US black population. This failure to provide information to hemoglobin C carriers will create an erroneous feeling of security—they would think that they could marry