Of 452 women who had been tuberculin tested twice with an interval of one year between tests, there were 105 who were pregnant at the first test and 121 others who were pregnant at the second test. An equal number of matched control subjects were selected who were not pregnant on either occasion. All 3 groups showed slight and similar increases in median diameter of induration during the one-year interval. There was no indication that pregnancy affected the level of tuberculin sensitivity.