Context: Self-myofascial release (SMR) is an intervention popularly used by rehabilitation, fitness, and sports professionals to improve recovery and performance. In SMR, the athlete/patient applies pressure to the muscle and fascia using various tools, such as balls, rods, foam rolls, and massagers. Objective: This study aimed to evaluate the acute effect of 2 SMR protocols (short term and long term) of the posterior thigh and calf muscles on hip and ankle range of motion (ROM) in physically active men. Participants: A total of 14 adult males (24.9 [3.2] y, 77.2 [13.2] kg, and 1.75 [0.06] m) who exercise regularly (at least twice a week, 45 min per session) participated in this study. Interventions: Participants performed a short-term SMR protocol (2 × 10 repetitions, SSMR) and a long-term SMR protocol (2 × 20 repetitions, LSMR) of the posterior thigh (using a foam roller) and calf (using a massage stick) muscles in counterbalanced order, on 2 different days with a 48-hour interval. Main Outcome Measures: Ankle dorsiflexion and hip-flexion ROM, evaluated at 5 moments: pre- and post-SSMR, pre- and post-LSMR, and in the control condition, which was always performed at the first visit. Results: The SMR promoted significant gains for both dorsiflexion (F_1,13 =202.67, P < .001, ${\eta }_{\mathrm{p}}^2=.94$) and hip flexion (F_1,13 = 66.46, P < .001, ${\eta }_{\mathrm{p}}^2=.84$), regardless of the protocol and limb analyzed. The average increase for both limbs corresponded, approximately, to 11% for ankle dorsiflexion and to 6% for and in hip flexion. Conclusions: The results suggest that SMR of the posterior thigh and calf muscles acutely increases the ROM of both hip flexion and ankle dorsiflexion and that duplicating the SMR volume from 10 to 20 repetitions per set seems not to promote additional gains.