The early signs of bronchial obstruction in smokers - obstruction of the small airways are discussed in the article. It is shown that the more informative spirometric signs of distal obstruction are flow measured at the end of the flow-volume curve and FEF25-75 versus FEV1, FVC and FEV1/ FVC. Diagnostic value of capnometry and nitrogen washout test are shown, which make the possibility to identify changes of the respiratory zone and small airways obstruction with normal spirometric values.