Subacromial impingement syndrome (SIS) is a frequent cause of shoulder pain. Our purpose in this double-blinded, randomized, and controlled study was to demonstrate whether the pulsed electromagnetic field (PEMF) provides additional benefit when used with other conservative treatment modalities in acute phase rehabilitation program of SIS. Forty-six patients with unilateral shoulder pain who had been diagnosed as having SIS were included in this trial. The cases were randomly separated into two groups. All cases received a treatment program for 3 weeks consisting of Codman's pendulum exercises and subsequent cold pack gel application on shoulders with pain 5 times a day, restriction of daily activities that require the hands to be used over the head, and meloxicam tablet 15 mg daily. One group was given PEMF; the other group was given sham PEMF daily, 25 min per session, 5 days per week for 3 weeks. Shoulder pain during rest and activity and which causes disturbance of sleep was evaluated using a visual analogue scale, and total Constant score investigated shoulder function. Daily living activities were evaluated by shoulder disability questionnaire. Results were assessed before and after treatment. When compared with the baseline values, significant improvements in all these variables were observed at the end of the treatment in both groups (p < 0.05). No significant difference between treatments was observed for any of these variables (p > 0.05). There is no convincing evidence that electromagnetic therapy is of additional benefit in acute phase rehabilitation program of SIS.