Although hypercholesterolemia has been recognized as a risk factor for coronary heart disease (CHD) for decades, only in recent years have clinical trials definitively shown the efficacy of lowering serum cholesterol to prevent the occurrence or worsening of CHD. In 1985, an NIH consensus conference published guidelines for the diagnosis and treatment of hypercholesterolemia. Prior to 1985, physicians and lay people alike were not yet convinced of the necessity to know one's cholesterol level, nor did they know what levels should be treated. In a community-based survey of cardiovascular risk factors, known as the San Antonio Heart Study, in which 1,932 Mexican-Americans (MAs) and 1,133 non-Hispanic whites (NHWs) were examined between 1979 and 1985, the authors found that only 36/501 MAs (7%) and 54/312 NHWs (17%) in the moderate- or high-risk categories were aware that their cholesterols were high. Of the total number aware, including those whose cholesterol levels were in the low-risk range, only 23/97 MAs (24%) and 29/108 NHWs (27%) were receiving dietary or drug treatment. Of those being treated, only 9/23 MAs (39%) and 12/29 NHWs (41%) were effectively controlled. Mexican-Americans were less likely to be aware of their hypercholesterolemia than non-Hispanic whites, but both ethnic groups had low levels of treatment.