Abstract: A diagnostic tool for pulmonary diseases comprises a display unit (2) for displaying predefined diagnostic questions relating to the pulmonary disease and for outputting a diagnostic prognosis on the disease, an input unit (4) for receiving responses from a user to the diagnostic questions displayed on the display unit (4), a storage unit (8) for storing the predefined questions and the interactively input responses, a calculation unit (6) for assigning each received response a predetermined count value, adding up the count values obtaining a final count value, assigning the final count value the diagnostic prognosis using a pre-defined result table (15) stored in the storage unit (8). The diagnostic tool according to the present invention allows the general practitioner or the patient to carry out a fast first diagnosis on functional lunge disease, in particular COPD. If a high probability, for example in percentage points, is established, further, more detailed diagnostic steps may be undertaken.