In previous papers1 we reported the observations on successive roentgenograms of the chests of 130 children with measles. It was shown that shadows suggesting pulmonic infiltration were present in 62.4 per cent of the patients less than 4 years of age and in 42.2 per cent of the patients 4 years of age or over. In the cases showing infiltration, this was present in at least 61 per cent before or during the height of the eruption. The infiltration was often present in cases that were considered clinically mild. Abnormal intensity of the pulmonary markings, pleuropulmonary changes and progressive and retrogressive hilar changes were also present. The enlargement of the hilar shadow was presumably due mainly to engorgement of the blood vessels, and to a lesser extent to swelling of the hilar lymph nodes. Viethen 2 found similar changes during measles and showed that the pulmonary infiltration persisted without