This paper reports the results of an open study to assess the efficacy (433 patients) and tolerance (453 patients) of spiramycin adipate given by slow intravenous infusion to treat severe acute bronchopulmonary infections in adults. Efficacy was good in 80.4% of patients. More specifically, high efficacy was obtained in 76.5% of 85 pneumococcal respiratory infections, 72% of 50 Haemophilus influenzae and H. parainfluenzae infections, 100% of 18 Mycoplasma infections, 100% of 16 Chlamydia infections and 93% of 14 Legionella infections. Tolerance was good in 83.5% of patients, moderate in 15.4% and poor in 6%. Venous irritation was the most frequent complication, observed in 16.3% of patients. No serious complication or sequel was observed. The authors conclude that spiramycin adipate constitutes an appropriate first-line treatment of acute bronchial and/or pulmonary infections in adults. While inferior to benzylpenicillin against Mycoplasma, Chlamydia and Legionella, spiramycin is as active as, and better tolerated than, erythromycin.