The aim of this study was to explore the effects of guided imagery relaxation in people with chronic obstructive pulmonary disease (COPD) using a randomized controlled design. Half of 26 participants were allocated to the treatment group in which six practice sessions on guided imagery were conducted, while the control group was instructed to take rest quietly during the six sessions. At the seventh session, physiological changes: partial percentage of oxygen saturation; heart rate; upper thoracic surface electromyography; skin conductance; and peripheral skin temperature were recorded during a 30-minute session with a sampling frequency of one minute. Repeated measures analysis of variance was used to explore the changes of the parameters between the groups. Mann-Whitney U test was used to compare the change of perceived dyspnoea between the groups. Results showed there was a statistically significant (p < 0.05) increase in partial percentage of oxygen saturation in the treatment group, but no significant effects on the other physiological parameters. Further study exploring the psychological effects of guided imagery is suggested.