The results which were obtained with the "Survey on the prevalence of tuberculosis infection in school children of the first grade of Public Schools in the city of S. Paulo, Brazil, are presented. One hundred and four Public Schools were studied, covering 29,009 subjects. All children were submitted to a standardized Tuberculin Test/WHO, with P.P.D. Rt 23 2 UT. From the 29,009 tests, 27,434 were interpreted, and the results obtained were: 91.4% non-reactors; 1.6% weak-reactors and 7% strong reactors. These rates increase from 6.3% in children of 6 years old to 16.1% in children of 10 and more years old.
