✓ Acute pulmonary edema after a large air embolus occurring during neurosurgery is a recognized phenomenon. The authors describe the course of a 76-year-old man who presented with noncardiogenic pulmonary edema shortly after undergoing resection of a high convexity meningioma. Transthoracic Doppler sonography, however, showed no evidence of a large intraoperative emboli; the evidence for ongoing but low-magnitude air embolus included visualization of bone aspiration of irrigant before bone-edge waxing, transient intraoperative declines in end-tidal CO2 tension, and an increase of the fraction of inspired oxygen to maintain adequate saturation after removal of the craniotomy flap. There was no hemodynamic instability noted. The airspace disease was self-limited and resolved on supportive treatment after approximately 1 week, as would be expected for pulmonary edema caused by a single large intravenous air embolus. The authors present this case as the first report of pulmonary edema resulting from low-level air embolus occurring during craniotomy. This situation may go unrecognized intraoperatively but can cause the same significant postoperative morbidity as larger, more easily identified air emboli.