A prospective, double blind study was conducted to determine the degree of concordance of pen and palpation methods of measuring skin induration to Mantoux tuberculin tests. One hundred thirty-five skin tests were performed in patients with previously bacteriologically proved tuberculous disease. An experienced reader who was only able to see the forearm of the patient measured the induration by the palpation technique. The measurement was then repeated by the pen method under the same conditions, on the same day. Results of the study indicated that the pen method yielded statistically the same frequency distribution of indurations as the palpation method and the pen method appeared to be more sensitive.