Chronic obstructive pulmonary disease (COPD) is an important world health problem and estimated that the prevalance will increase. In early period this disease in symptomatic with cough, sputum and dyspnea. FEV1/FVC was greater than 70% in early period and it was accepted as stage 0 (at risk) COPD before the last The Global Initiative for Chronic Obstructive Lung Disease (GOLD) guideline. In last GOLD guideline this stage is excluded. In this study we aimed to find out the clinical differences between this cases and healty population. Prospectively spirometric measures, exercise capasity, dyspnea index, saturation of O-2 (SpO(2)) and life quality are compaired between two groups. We evaluated 58 at risk cases and 63 healty adults. There was no difference between two groups about age, sex and smoke sessations. In at risk group 77.6% cough, 53.4% sputum and 62.1% dyspnea were the symptoms. In curently smokers cough and sputum were dominant symptoms however dyspnea was dominant symptom in exsmokers. Absolute FEV1, FEF25-75 values, predicted FEV1/FVC, FEV1, FVC, PEF, FEF25-75 % values are lower in at risk group (p0.05). Dyspnea index before walking were not different between two groups (p>0.05) however dyspnea index after walking and change were higher in at risk group (p>0.05). Resting SpO(2), SpO(2) after exercise and desaturation with exercise (Delta SpO(2)) were lower in at risk group but not statisticaly significant. Physical and mental components of Short Form 36 (SF36) scores were similar in two groups (p>0.05). COPD at risk group is seperated from healty population with chronic respiratory symptoms and inhalation of smoke or other irritans. In these cases spirometric measures are significantly worse although functional parametres are similar with healty population, so it is thought about being a subclinical disease. These cases must be educated about COPD, encouraged about giving up smoking and prevented occuring COPD
