Studies which specifically examined the relationship between VO2 and WR during exercise in patients with COPD repor-ted normal or higher slope values, despite lower VO2max values and reason of this fenomenon is unknown. Aim: The aim of this study is to examine the relationship between VO2 and WR during exercise in patients with airflow li-mitation. 51 COPD patients and 25 sedentary healthy individual were studied. Exercise tests performed with cycle ergometry and work increments were 15 watt at per minute. Categorization of airflow obstruction was determined as mild, moderate and severe according to the ERS consensus statement 1995. Results: Resting VO2 was not significantly different between the groups, either directly measured or normalized for body weight (p>0.05). The VO2max- ualue was significantly reduced in the patients with moderate and severe airflow obstructi-on, compared with the normal subjects. When the relationship between VO2 and WR were analysed, analysis of varianceshowed no differences in the slope across the various groups, although a trend toward a higher slope in the more severely obstructed groups was noted [in controls: 10.31 (2.27), mild: 9.38 (3.06), moderate: 10.76 (3.67) and seuere:11.59 (3.24) mlO2/min/W(mean(SD) p>0.05]. None of the PFT and exercise parameters were related VO2/WR slope according to step-wise regressions. Conclusion: This study demonstrated that the relationship between VOs-WR during exercise is similar between patients with airflow limitation and those with normal results of pulmonary function tests. Furthermore, the degree of airflow limi-tation had no impact on the slope of VC>2 on WR.