SummaryPseudomembranous and obstructive Aspergillus tracheobronchitis (PMATB/OATB) are still considered to be refractory to therapy and to have a fatal outcome. To evaluate the optimal diagnostic strategy and to describe factors affecting the outcome of PMATB and OATB. Retrospective analysis of four new cases of PMATB and OATB combined with 16 previously reported cases over a 10‐year period (1995–2004). Among the four new cases reported and the 16 published cases, four patients survived their infection. The mortality rate was significantly higher in the group of ventilated patients [94% (15 of 16 patients)] than in the group of non‐ventilated patients [25% (1 of 4 patients), P < 0.05, Fisher's exact test]. In all 20 patients, diagnosis was established by bronchoscopy. Culture examination of mucous plugs was positive in 8 of 10, culture of the tracheobronchial aspirate was positive in 8 of 12, and bronchoalveolar lavage was diagnostic in 7 of 13 patients. All bronchoscopic techniques were complementary in improving the yield of bronchoscopy. However, microscopy of mucous plugs and/or necrotic material was the best diagnostic modality [positive in 94% (17 of 18 patients)]. Prognosis of PMATB and OATB remains poor. Microscopy of respiratory specimens is the most sensitive tool to confirm the diagnosis. The characteristic appearance of the disease makes it possible to start antifungal therapy immediately.