SummaryThe authors studied the effectiveness of a compound drug, sulphamethoxazole-trimethoprim, in acute pulmonary disease of moderate gravity. :They reviewed the numerous criteria used in medical papers during clinical trials concerning antibiotics. They emphasized the value of transtracheal aspiration for the correct interpretation of the bacteriological flora in the tracheo-bronchial tree. The treatment was effective in 24 cases (19 good and 5 fair) over 31 (70 %). No toxic reaction was noted during this short term trial.