The diagnosis of clinical tuberculosis in a student at an Alabama high school in March 1969 prompted skin testing of 379 students and 147 additional contacts. The skin positivity rate among the students was 77% and seven additional clinical cases were uncovered. In May 1969 seventeen students who had initially had negative or doubtful reactions had converted, but no new clinical cases were found. In October 1969 four new reactors (1.7%) among students who had attended the implicated school during the previous school year were found.