We studied pulmonary mechanics both before and 45 minutes after chest physiotherapy according to Vojta in 11 spontaneouslv breathing infants (birth weight < 1500 gm, mean age at time of study 16 weeks, range 9-26 weeks) with bronchopulmonary dysplasia (BPD). The physiotherapist exerted a pressure with his thumb onto the 6th anterior rib at the level of the midclavicular line in the direction of the spine for several minutes. The full reflex response that was required according to the study protocol consisted of the typical change in whole-body positioning with an extension of the spine, chest expansion, and a contraction of the ahdominal wall muscles. We measured continuosly the airflow of spontaneous breathing with a pneumotachometer and the esophageal pressure with a miniature pressure sensor. The signals were online digitized and processed by a computer. For each measurement, at least 80 breathing cycles were evaluated. After Vojta's therapy, lung compliance was higher (P = 0.006 paired t-test) and the ratio work of breathing per tidal volume was smaller (P = 0.002). Airway resistance tidal volume, and minute ventilation did not change. We conclude that Vojta's therapy may transiently improve pulmonary mechanics and reduce work of breathing in infants with BPD. We therefore suggest to implement Vojta's therapy in the management of BPD.