Knee osteoarthritis (OA) is perceived as a major public health problem, and today, various treatment modalities are used to manage this condition. The purpose of this study was to assess and compare the efficacy of transcutaneous electrical nerve stimulation (TENS) and intra-articular hylan G-F 20 (Synvisc; Genzyme Corporation, Ridgefield, NJ) in patients with symptomatic knee OA. A total of 60 patients with primary knee OA were randomized into 2 treatment groups. TENS was applied for 3 weeks in the first group, and in the second group, hylan G-F 20 was injected intra-articularly once a week for 3 weeks. Patients were then followed for 6 months. Disease severity was measured with the Lequesne Index. Efficacy in terms of pain, functional status, and quality of life was assessed through analysis of changes in Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and short Form 36 Health Survey (SF-36) scores. Adverse events were monitored throughout the study. WOMAC pain scores were improved at the first control visit in the TENS group and in the viscosupplementation group; this improvement was statistically significant. WOMAC stiffness scores showed a statistically significant decrease in the TENS group at the first control visit. Stiffness did not decrease during the first month in the second group; however, these patients exhibited improvement during the sixth month after injection. Physical function scores and SF-36 total scores did not change in either group after treatment. Pain relief was observed at the first month and continued throughout the 6-month follow-up period in both groups. Stiffness decreased by the sixth month in both groups. Improvement in WOMAC physical function scores was greater in the intra-articular hylan group than in the TENS group at the end of follow-up; however, quality of life was not improved in either group. These therapies used in combination may alleviate symptoms in patients with OA.