56 patients with shoulder impingement syndrome were randomized to receive treatment comprised of either 3-weeks of active pulsed electromagnetic field (PEMF) therapy or placebo PEMF, followed by a 6-week shoulder exercise program. The purpose was to evaluate the efficacy of PEMF in improving pain, function, and muscle strength. Results revealed that patients in the active PEMF therapy group experienced improvements in pain and function at all time points (following PEMF therapy at 3 weeks and following shoulder exercise at 9 weeks and at 3 months) when compared to baseline, whereas improvements were only observed after completion of shoulder exercise program in the placebo group. Muscle strength was improved in the active group after exercise at 9 weeks (lateral and medial rotation) and 3 months (medial rotation). However, no between-group differences were observed for any of the outcomes. A larger proportion of patients in the active group exceeded the minimal clinically important difference for pain and function.