Alterations in pulmonary surfactant are partly responsible for the respiratory insufficiency seen under septic shock process. We have used an experimental model of LPS-induced shock in rats to examine the cells responsible for the pulmonary surfactant synthesis and its relationship to lung injury. (14C)Choline incorporation into phosphatidylcholine was significantly reduced in lung homogenates or type II cells obtained from LPS-treated animals. Addition of LPS in vitro fails to increase (14C)choline incorporation in type II cells obtained from LPS-treated animals. We suggest that this depression of pulmonary phosphatidylcholine synthesis may partly explain the occurrence of respiratory failure with septic shock.