OBJECTIVE: To evaluate the efficacy of classical pulsed electromagnetic field therapy on patients with knee osteoarthritis. METHODS: The databases PubMed, EMBASE, Web of Science and Cochrane Library were searched for relevant studies. Randomized controlled trials comparing classical pulsed electromagnetic field with placebo for patients with knee osteoarthritis were included. Data for primary outcomes, including pain, stiffness and physical function, were extracted. Data from 8 randomized controlled trials involving 421 patients were pooled. RESULTS: Pulsed electromagnetic field therapy had an effect on improving physical function (weighted mean difference; WMD = -5.28, 95% confidence interval; 95% CI -9.45 to -1.11, p = 0.01), but showed no advantage in the reduction of Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) total score (WMD = -7.80, 95% CI -16.08 to 0.47, p = 0.06), WOMAC pain score (WMD = -1.06, 95% CI -2.30 to 0.17, p = 0.09), visual analogue scale pain score (WMD=-0.88, 95% CI -2.06 to 0.31, p = 0.15) or WOMAC stiffness score (WMD = -0.50, 95% CI -1.09 to 0.09, p = 0.1). CONCLUSION: Pulsed electromagnetic field therapy is beneficial for improving physical function despite having no advantage in treating pain and stiffness. Further randomized controlled trials are needed to confirm these findings and determine the optimal parameters and treatment regimen for pulsed electromagnetic field therapy.