This paper refers to a Multicentric Quality Control Program on spirometry performed in Buenos Aires city. Seventeen spirometers (9 water seal, dry rolling seal or bellows, 5 flow detection type and 3 peak-flow meters) owned by 8 different Hospitals were tested. Reference values were obtained by means of an Explosive Decompression Simulator calibrated against a Stead-Wells bell spirometer, which meets ATS recommendations. Only 42% (6/14) of the tested spirometers agreed with the ATS minimal requirements with regard to FVC and FEV1; volumetric spirometers performed better than flow detectors. The maximal error was 11% when measuring a FVC of 3.41 L. Peak flow showed a very high inter-instrument coefficient of variation. The need of frequent quality control checks is stressed.