64 patients with delayed union following a long-bone fracture were randomized to receive either an active or sham treatment of pulsed electromagnetic field (PEMF) therapy between 16 weeks and 6 months postoperatively to determine whether early application of PEMF is effective in improving union success rates in these patients. Results indicated that, although union success rates were similar between groups at the 3-month assessment, PEMF therapy was associated with a significantly higher union success rate at study completion, compared to the control group (77.4% versus 48.1%). The average length of treatment at the end of the study was similar between groups.