Introduction: Physical exercise can improve patient outcomes and reduce hospitalization and mortality rates among subjects with chronic obstructive pulmonary disease. This study aimed to compare the effects of upper limb and breathing exercises on six-minute walking distance among these patients. Material and methods: This three-group randomized controlled clinical trial was conducted in 2017-2018 in Velayat hospital, Qazvin, Iran. Seventy-five patients were purposively selected from the outpatient lung clinic of the hospital and randomly allocated to either the 25-patient groups of upper limb exercise, breathing exercise, or control. The patients in the first group were performing upper limb exercises thrice weekly for one month in the study setting. Their counterparts in the second group were doing pursed-lip and diaphragmatic breathing exercises four times daily for one month at their homes. However, the patients in the control group received no exercise intervention. Six-minute walk test was performed by each participant both before and after the study intervention. The SPSS for Windows program (v. 23.0) was used to analyze the data via the Chi-square test, the paired-sample t test, and the one-way analysis of variance. Results: Before the intervention, the groups did not significantly differ from each other respecting six-minute walking distance. During the study, walking distance in the control group did not change significantly, while it remarkably increased in both the upper limb exercise and the breathing exercise groups (p < 0.05). After the intervention, walking distance in the upper limb exercise group was significantly greater than the breathing exercise group (p < 0.05) and the control group (p < 0.05); however, the difference between the breathing exercise and the control groups was not statistically significant (p > 0.05). Conclusion: Upper limb exercise is more effective than breathing exercise in increasing walking distance among patients with chronic obstructive pulmonary disease. Therefore, upper limb exercise can be used as a safe, simple, and inexpensive rehabilitation technique for these patients.