A case of pulmonary allescheriasis in a 53-year-old woman residing in London, Ontario, Canada, is described. This patient entered the hospital complaining of dyspnea, a productive cough, and pains in the neck and left shoulder. Roentgenograms of the chest revealed a large cavity in the upper lobe of the right lung, and xerograms showed an intracavitary mycetoma. Monosporium apiospermum, the imperfect form of the fungus Allescheria boydii, was grown from her sputum and from the mycetoma as well. Treatment with amphotericin B had no effect on the infection, and the upper lobe of the right lung was resected. The cough cleared completely and the patient made an excellent recovery. This case of pulmonary allescheriasis once again emphasizes that the most satisfactory form of treatment available at present for this mycosis is surgical excision of the infected area.