Rationale: Data on hemoptysis of unknown origin (so-called 'cryptogenic') are scarce and their outcome remains controversial. Objectives: To describe the clinical spectrum and course of patients with cryptogenic hemoptysis, as well as pathological findings when surgery is performed. Patients and methods: A cohort of 81 patients referred for cryptogenic hemoptysis after clinical evaluation, chest radiography, fiberoptic bronchoscopy and CT scan to a respiratory intermediate care and intensive care unit, from December 1995 to August 2004. A prospective follow-up by visit or telephone interview. Results: The 81 patients (69 males) had a mean cumulative volume of hemoptysis averaging 190 mL on admission. First-line conservative measures and bronchial artery embolization (BAE) controlled hemoptysis in 73 patients (90%). Emergency surgery was performed in 6 patients (7%) because of failure of BAE and secondary scheduled in a 7^th patient. Seventy-three patients were followed-up for a mean of 47 ± 35 months. No lung cancer developed. Hemoptysis recurred in 10 patients (4 within the first year, 6 between 1 and 8 years later), 2 of whom underwent surgery. A specific bronchial vascular involvement (Dieulafoy disease) was demonstrated in 5 of the 9 operated patients, especially in those with high amounts of bleeding. Conclusions: Cryptogenic hemoptysis may be a life-threatening condition. Non-surgical approaches provide immediate control of bleeding in most patients with cryptogenic hemoptysis, with few recurrences on both short and long terms. Dieulafoy disease of the bronchus, unsuspected after routine imaging investigations, may be involved in a subset of patients to be determined.