Carbon monoxide (CO) poisoning is a leading cause of poison-related morbidity and mortality worldwide. By binding to hemoglobin and other heme-containing proteins, CO reduces oxygen delivery and produces tissue damage. Prompt treatment of CO-poisoned patients is necessary to prevent acute and long-term complications. Oxygen therapy is the only available treatment. Visible light has been shown to selectively dissociate CO from hemoglobin with high efficiency without affecting oxygen affinity. Pulmonary phototherapy has been shown to accelerate the rate of CO elimination in CO poisoned mice and rats when applied directly to the lungs or via intra-esophageal or intra-pleural optical fibers. The extracorporeal removal of CO using a membrane oxygenator with optimal characteristic for blood exposure to light has been shown to accelerate the rate of CO illumination in rats with or without lung injury and in pigs. The development of non-invasive techniques to apply pulmonary phototherapy and the development of a compact, highly efficient membrane oxygenator for the extracorporeal removal of CO in humans may provide a significant advance in the treatment of CO poisoning.