Background:The normal values of alpha-amylase in humans is unknown.Objective: To determine the normal values of alpha-amylase activity in humans. Material and methods:From October 2009 to June 2011 we studied 111 patients referenced to thoracic service to be submitted to bronchoscopy. The patients were positioned in supine position, performed local antisepsis and anesthetized with 2% lidocaine . Thereafter we introduced a needle into catheter by puncturing the cricothyroid membrane using a 14G cateter. Finally we introduced ten milliliters of saline and immediately aspirated with the maximum power of the vacuum system. The samples were sent for α-amylase activity determination by CNPG method. Results:The activity of α-amylase of tracheal aspirate ranged from 24 to 10.000 IU/l), and a mean 1914IU/L. The levels had no statistical differences according age, sex, race, smoking history and the lung diseases.Conclusion: we could define the probably physiologic levels of amylase activity in humans beings.