Adenoviral-mediated gene transfer to the lung has been used experimentally in cystic fibrosis and has possible clinical application for several other neonatal lung diseases. Delivery of the adenoviral vector to the lung by saline instillation has resulted in patchy distribution. Liquid ventilation with perfluorochemical (PFC) has been used in both animal models and humans, improving both drug delivery and oxygenation. To evaluate adenoviral distribution with PFC (Perflubron: LiquiVent®, Alliance Pharm. Corp.), 6 juvenile rabbits (2.5±0.2 kg) were anaesthetized (ketamine and pentobarbital) and intubated. The recombinant adenovirus AdCBlacZ (1011 particles/kg) suspended in saline (1.5 ml/kg) was instilled through the ET tube with air (controls, n=3) or simultaneously with PFC liquid (15 ml/kg, n=3) given in 4 aliquots (half with the right lung dependent and half with the left lung dependent) with intermittent hand ventilation. After extubation, animals recovered breathing spontaneously. Serial x-rays determined that≈90% of the PFC evaporated from the lungs by day 4. All 6 animals tolerated the saline and PFC instillations with no adverse effects; on day 4, lungs were removed, lobes divided into 12-24 regional parts, and pieces fresh-frozen for X-gal staining (2 rabbits) or stored (-70 C) for β-galactosidase(β-gal) activity assay. With PFC, total parenchymal β-gal activity was 2-3 fold higher (tracheal activity decreased) and distribution of activity among lobes more closely approximated lobar weight. Relative distribution of activity to the distal 1/3 of the caudal lobes was 2-fold greater (p<0.01) with PFC vs saline. X-gal staining showed greater punctate distribution of positive cells in distal regions of the PFC lungs. PFC had no adverse effect on viral infectivity or cell growth in monolayer cultures of the pulmonary A549 cell line. This study demonstrates the feasibility and efficacy of Perflubron as a vehicle for delivery of viral vector to distal regions of the lung parenchyma. We speculate that PFC liquid may be of particular benefit in distributing agents to atelectatic regions of the damaged lung.