Pulmonary endothelium plays an important role in the maintenance of normal pulmonary physiology and its dysfunction is involved in a number of pulmonary diseases. Correction of endothelial dysfunction via antisense oligodeoxyonucleotides (ODN) is dependent on the development of a delivery vehicle that can efficiently deliver the ODN to pulmonary endothelium with minimal toxicity. To this end, we have developed a lipidic vector (LPD) that is composed of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) liposomes, protamine, and ODN. This formulation is highly efficient in delivering ODN to the lung via the vascular route. The efficiency of delivery is a function of lipid composition and of the charge ratio between lipid and ODN. Immunofluorescence staining of BrdU-labeled ODN suggested efficient accumulation of ODN in the alveolar capillary region. Transmission electron microscopy of immunogold localization of BrdU-labeled ODN confirmed that pulmonary endothelial cells were indeed targeted by the vector. Furthermore, this formulation is associated with minimal proinflammatory cytokine response and other hematologic toxicities when the ODN lack a potent unmethylated CpG motif. Pretreatment of mice with LPD containing an ODN against intercellular adhesion molecule-1 (ICAM-1) significantly decreased ICAM-1 expression in the lung following LPS challenge. These results provide a basis for lipid-mediated delivery of ODN for the treatment of pulmonary diseases.