Summary Four cases of nosocomial aspergillosis are described where the responsibility of pleural drainage is advocated. Infection was pulmonary once, pleural three times. Pleural suction had been long lasting with incomplete re-expansion of the lung and major air leaks. The hypothesis of the responsibility of pleural drainage in the advent of aspergillosis is reinforced by the revision of medical papers, which leads to the conviction that similar cases have been described yet, even though the mechanism of the contamination had not been understood. Prevention needs to limitate the lasting of the suction, especially if there are major air leaks. Cure needs total re-expansion of the lung and suppression of any pleural cavity, even if a thoracoplasty is needed. An anti-fungal therapy is not always needed.