Starting from the premise that in the methodology of tuberculosis control priority should be given to the higher risk groups, the authors tried to identify such groups and list them in the order of their priority within the district of a dispensary serving a population of about 400,000 inhabitants. On comparing the results of the detection of risk factors among the population in general with that per endangered groups it was found that the former presented a decrease (from 1.09 to 0.44 per thousand) and the latter an increase (from 0.91 to 1.5 per thousand). The 126 747 examinations for risk factors revealed a succesive increase in the detection indices as follows: 0.76 per thousand among students, 1.36 per thousand in silicogen risk enterprises, 2.07 per thousand among the workers on building sites, 2.22 per thousand among diabetics, 2.76 per thousand among contacts, 2.85 per thousand among hyperergic subjects, 3.89 per thousand among former patients no longer on the files, 4.17 per thousand among alcoholics and patients under psychical treatment, 6.01 per thousand among patients with minimal lesions and 6.82 thousand among those with sequelae.