OBJECTIVE: Chronic Obstructive Pulmonary Disease (COPD) has symptoms such as impaired exercise tolerance and decreased quality of life. In this study, the effects on exercise performance and quality of life in COPD patients were compared when the quadriceps femoris (QF) and gastrocnemius (GC) muscles were strengthened by neuromuscular electrical stimulation (NMES) in stable COPD patients. MATERIAL AND METHODS: Forty-five patients with COPD were randomly divided into three groups as control, gastrocnemius muscle (GC Group) and quadriceps femoris muscle (QF Group). The control group received pulmonary rehabilitation only, the GC group received NMES to the GC muscle in addition to pulmonary rehabilitation, and the QF group received NMES to the QF muscle in addition to pulmonary rehabilitation. Patients were evaluated with Visual Analog Scale (VAS), Six Minute Walk Test, St. George's Respiratory Questionnaire (SGRQ), Short Form-36 (SF-36) and Beck Depression Inventory before and after treatment. Statistical analysis was performed in IBM SPSS 23.0 program and p<0.05 was considered significant. RESULTS: While there was no difference in VAS, physical function, Beck Depression, six-minute walk and fatigue test data before and after treatment in the control group (p>0.05), a statistically significant difference was found in the GC and QF groups (p<0.05). There was no significant difference between the groups in the pre and posttreatment values of all tests (p>0.05). CONCLUSIONS: Strengthening the QF or GC muscles seems to improve exercise performance and quality of life in patients with COPD. However, QF and GC muscle training in COPD were not superior to each other in terms of their effect on quality of life.