STUDY OBJECTIVES: To investigate the technical properties and user friendliness of 10 office spirometers devoted for use in general practice, and to compare the results with standard diagnostic spirometers. DESIGN: Multicenter study. SETTING: Ten spirometer models were tested independently in three pulmonary function laboratories and by three general practitioners (GPs). MEASUREMENTS: The laboratories studied the technical quality of the office spirometers in terms of precision and agreement with standard spirometers, whereas the three GPs assessed their user friendliness. The spirometers tested were as follows: Spirobank (Medical International Research; Rome, Italy); Simplicity (Puritan Bennett; Pleasanton, CA); OneFlow (Clement Clarke International; Harlow, Essex, UK); Datospir 70 (Sibelmed; Barcelona, Spain); Datospir 120 (Sibelmed); SpiroPro (SensorMedics; Yorba Linda, CA); EasyOne (NDD; Zurich, Switzerland); MicroLoop (Micro Medical; Chatham, Kent, UK); SpiroStar (Medikro; Kuopio, Finland); and Pneumotrac (Vitalograph; Maids Moreton, Buckingham, UK). FVC and FEV1 were measured in 399 subjects. User friendliness was assessed by the three GPs using a questionnaire. RESULTS: The precision of FEV1 of the office and standard spirometers was comparable, but three office spirometers had > 200 mL limits of precision for FVC. Some devices presented a proportional difference on the FEV1 with standard spirometers, underestimating the small values. The limits of agreements between standard and some office spirometers for FEV1/FVC ratio was > 10%. The overall user friendliness was estimated as good. CONCLUSIONS: The global quality and user friendliness of several office spirometers make them acceptable for the detection of COPD, although differences between the laboratory and some of the office spirometers values suggest that the misclassification rates may be increased when using some models of office spirometers.