Unilateral lung collapse (ULC) is a clinical challenge in the intensive care unit and requires sophisticated treatment approaches, especially if the collapse continued over several hours. If not responded to ordinary measures such as postural drainage and bronchoscopy, it may require insertion of a double-lumen endotracheal tube and independent lung ventilation or high-pressure manual re-expansion of the collapsed lung which may result in lung injury. In this article, a safe and gradual re-expansion method using airway pressure release ventilation is presented for the treatment of a ULC.