The updated recommendations of the American Thoracic Society (ATS) on the standardization of spirometry were highlighted. Factors influencing occupational spirometric testing included equipment selection and testing, equipment quality control, forced vital capacity (FVC) maneuver performance, measurement procedure, and acceptability and reproducibility. The ATS document outlined recommendations for accuracy of spirometers and gave test methods for validating performance. Preventive maintenance, calibration checks, verification, and quality control were stressed to assure accuracy of spirometric results. Recommendations were made for instructing and demonstrating the FVC maneuver to test subjects. An extensive description of the graphic recorders and visual displays needed for technicians to assess the quality of the spirogram was made. Three acceptable spirograms were considered necessary for accurate interpretation of findings. The recommendations were detailed in the 1987 ATS document; the authors conclude that attention to the recommendations can assist users in obtaining better data from spirometry.