A difficulty in the timely diagnosis of obstructive lung disease is a problem of modern medicine. The disease gradually develops through the years and manifests when bronchopulmonary system cannot be restored. The paper presents a method of early diagnosis of obstructive lung disease, assesses various procedures, and characterizes their informative value. There is evidence that the significance of routine functional tests increases with the progression of the disease. The simplicity of these tests and their assessment will assist a general practitioner to establish the diagnosis in time.