A 65-year-old man who had undergone a right upper lobectomy for squamous cell carcinoma developed a persistent air space in the right superior thorax. Because a bronchopleural fistula was suspected, a new technique to demonstrate the fistula was used. Five mCi of Tc-99m DTPA was instilled through a pigtail catheter into the cavity. Radiotracer activity extended into the remaining right bronchial tree, trachea, and left bronchial tree on the 10 minute delayed image confirming the presence of a bronchopleural fistula. Using bronchoscopic guidance, the fistula was sealed with a fibrin plug. A repeat examination 4 days later revealed no extension of tracer from the cavity up to 60 minutes after instillation, indicating successful sealing of the fistula. This technique offers a rapid, inexpensive, and portable diagnosis of bronchopleural fistula.