From December 1986 to January 1988, 100 General Practitioners and Pneumologists working outside hospital included in open unmatched series 275 patients who were diagnosed as having pneumonia at home. The study consisted of 53.2% men with an average age of 49.3 plus or minus 19.3. Their temperature on the first day (J1) was in 72.7% of cases greater than 38.5 degrees Centigrade. The doctors felt that the general state was good in 66.5% of the cases. Cough was present in 83.5% of cases but was dry in one out of every two. The patients received Amoxycillin in a dose of 2 grams per day orally (66.9%), or by injection (33.1%). On the third day (J3) 90% of the patients had a temperature below 38.5 degrees Centigrade. Their general state was improved in 94.6% of cases. The diagnosis of pneumonia at home was confirmed radiologically on 219 of the films available, confirming the good specificity of the clinical diagnosis of pneumonia at home. Ten patients were hospitalised. The apparent treatment of Amoxycillin was given in 247 cases (89.8% of cases). In 28 cases (10.2%) the treatment was changed by the addition or substitution of a Macrolide (15), or another antibiotic (5), and in 80 cases a change of treatment was not specified. 25 of these 28 cases were reviewed on the 14th day (J14) and no failures were observed after the change of treatment. In 247 patients in whom the treatment with Amoxycillin was followed 336 were reviewed on the 15th day and there had been four failures. Three were intolerant to the drug and there was one relapse.(ABSTRACT TRUNCATED AT 250 WORDS)