Objectives: The role of a myofascial release (MFR) on flexion contractures after total knee arthroplasty (TKA) has not yet been elucidated. Therefore, the purpose of this study was to determine its immediate effect on such patients. Methods: In this A-B single subject experimental study, 33 TKA's patients with knee flexion contracture had their gluteal, posterior fascia lata, posterior crural and plantar fasciae released. Patients' knee range of motion (KROM), pain and muscle electric activity were assessed pre- and post-intervention. Results: An increase in electric activity of the biceps femoris muscle was identified after treatment (pre RMS = 0.087 ± 0.066 V; post RMS = 0.097 ± 0.085 V; p = 0.037). Mean gain of KROM was 5.72 ± 6.27, correspondent to an 11.9% improvement (p = 0.01). Eight subjects had their pain decreased on 56.9% (p = 0.04). Conclusions: MFR increased muscle activity, reduced pain and improved the KROM of TKA patients. Thus, MFR is a useful resource of rehabilitation after TKA.