A questionnaire survey was performed on the use of investigations and their impact on treatment of adult lower respiratory tract infection in the community. Data on the management of 2,056 such infections were obtained simultaneously from general practitioners in France, Germany, Italy, Spain and the UK. Diagnostic tests were only performed in 29% of cases. Chest radiographs were performed most frequently (22%), followed by peripheral blood white cell count (15%) and microbiological examination of sputum (7%), with major differences being found in the frequency of these tests both by clinical diagnosis and country. A change in initial antibiotic therapy was made in 12% of cases, with use of investigation being significantly linked to such changes. Second- and third-line antibiotics were significantly different to first-line therapy, with macrolides the most frequently prescribed second-line and quinolones the most frequently prescribed third-line antibiotics.