Session ratings of perceived exertion (SRPE) provide a valid and reliable indicator of resistance exercise session intensity. However, there is a lack of studies on the effects of resistance exercise with blood flow restriction (BFR) on SRPE. Thus, the aim of this study is to compare the effects of resistance exercise at high intensity versus low intensity with BFR on internal training load measured by SRPE. Thirteen young (22.2 ± 3.8 years) resistance-trained men (training experience 3.2 ± 2.4 years) participated in the study protocol. After determining one maximum repetition (1-RM), the subjects were assigned to two groups in a counterbalanced design (i) high-intensity exercise (HIE, performed one training session at 80% of 1-RM) and (ii) low intensity with BFR (BFR, performed an exercise session at 50% of 1-RM with BFR). During each session, subjects performed three sets of unilateral elbow flexion leading to concentric failure with a 1-min rest interval between sets. A cuff around the arm, inflated at 110 mmHg, was used continuously for BFR. The SRPE was reported 30 min after the end of the session. The low intensity with BFR showed lower total work (197.13 ± 63.49 versus 300.92 ± 71.81 kg; P = 0.002) and higher SRPE (9 versus 6; P = 0.007) than high-intensity resistance exercise. The present results indicate that BFR is an important factor to increase internal training load. Future studies should investigate the physiological stress imposed by different training methods rather than just quantify the external training load such as intensity or volume.