A review of clinical records of the past 10 years at the Cincinnati General, Cincinnati Veterans Administration, Christ, Good Samaritan, Jewish, and Holmes Hospitals, Cincinnati, yielded 25 patients with proven pulmonary blastomycosis. Eleven presented with findings suggestive of a diagnosis of primary carcinoma of the lung and one with carcinoma of the larynx and pulmonary metastases. The clinical presentation was varied; three were asymptomatic. Seven of the 12 underwent major surgical procedures before the diagnosis was apparent. An eighth was diagnosed by laryngeal biopsy. Three of the remaining four were bronchoscoped but were actually diagnosed when previously collected sputums grewBlastomyces dermatitidis.The remaining patient had pulmonary infiltrates, a bone lesion, and a positive skin biopsy for blastomycosis. An expeditious diagnostic approach is warranted when carcinoma is suspected, but prudent attention to the possibility of blastomycosis might save an occasional patient an otherwise unnecessary surgical procedure.