[Lung function testing --the Official Guideline of the Japanese Respiratory Society].

This review article introduces the official guideline for the lung function testing firstly established by the Japanese Respiratory Society in November 2004. The members of the Japanese Society of Laboratory Medicine were also included in the working group to make the guideline. A central goal of the guideline is to standardize the skill of lung function testing and thus minimize its variability. The guideline includes the chapters for spirometry, flow-volume curve, and diffusing capacity of the lung, where principles and quality controls are introduced with reference values for each testing. Furthermore, the algorithm for differential diagnosis using the lung function testing is demonstrated in the last chapter. The lung function testing can bring a strong impact on patients' lifestyle and future treatment plan. We sincerely hope that this guideline will contribute to routine laboratory practice.