Objective: To analyze the physiological response associated to the application of the 6. MWT in Chilean COPD patients. Method: In this descriptive, cross-sectional study, 30 patients (70.97. ±. 8.89 years), with moderate ventilatory impairment (%FEV1. = 58.83. ±. 7.92) completed the 6. MWT. Heart rate (HR), partial arterial saturation (SpO2), rating of perceived effort (RPE), and fatigue of lower limbs (LL) were measured at each minute of the test. In addition, these variables were recorded at 4. minutes after completing the test. Results: The patients completed 106.63%. ±. 22.16 of the predicted distance. RPE and fatigue of LL increased significantly (P<. .05). On average, the subjects used approximately 50% of their HR reserve without exhibiting desaturations. After 4. minutes of post-test rest, HR did not reach pre-test levels. Conclusion: 6. MWT generates significant increases in the cardiac chronotropic response, RPE and LL fatigue that remains higher, even after four minutes of post-test rest. This could reflect functional alterations that go beyond the performance measured just in terms of distance covered. © 2013 Asociación Española de Fisioterapeutas.