Objective: Primary dysmenorrhea (PD) is a chronic health condition that affects primarily young women and interferes with daily activities, causes loss of work productivity, and reduces quality of life. Transcutaneous electrical nerve stimulation (TENS) is a complementary and alternative therapy used to reduce pain related to PD. The purpose of this meta-analysis study was to evaluate the effectiveness of TENS in the treatment of pain in women with PD. Methods: A search of the English literature in the Cochrane Library, MEDLINE (EBSCO), Physiotherapy Evi-dence Database (PEDro), CINAHL (EBSCO), PUBMED, OVID, Science Direct, Scopus, Academic Search Complete databases was conducted using combinations of the following search terms: 'primary dysmenorrhea', 'pain', 'transcutaneous electrical nerve stimulation', 'TENS', and 'electrical stimulation'. All content from database inception through April 2020 was included in the search. Results: The initial search strategy based on date range and language yielded 571 relevant records and 4 of them were about both TENS and PD. A total of 260 patients were enrolled in the included studies. In all of the included studies, the comparison intervention consisted of sham TENS. The primary outcome of interest was pain intensity. Our analysis indicated that TENS was statistically more effective than sham TENS in reducing PD-related pain (SMD=1.384; 95% CI=0.505, 2.262; p = 0.002). Conclusion: TENS is a safe and well-tolerated electrophysical therapy that may be effective for relieving pain in PD. (c) 2020 Elsevier Inc. All rights reserved.