Intramuscular stimulation (IMS) therapy has been used widely ever since Gunn introduced the effect of IMS in his study in 1980. Usually IMS has been based on Cannon's radiculopathic model, known for its effectiveness in chronic pain relief. In this study we systematically review the effectiveness and safety of IMS. In order to accomplish a systematic review, we searched for IMS-related studies through 12 bibliographical databases and 19 studies were included (4 randomized controlled trials (RCTs), 2 non-RCTs and 13 case reports/studies). Study selection was conducted independently by two researchers based on title and abstract. As a result, most included studies of 16 showed significant improvement in range of motion, decrease of drug consumption as well as pain relief after IMS treatment; the other 3 studies reported adverse events. In terms of the effectiveness of IMS, the results of intervention were good, so we concluded that IMS therapy is a useful method of pain treatment; with respect of safety, few adverse events that could have been caused by IMS were observed. However, it is not certain that there was a causal relationship between IMS and the adverse events that were reported due to a lack of evidence. Therefore, clinicians who have sufficient knowledge and experience of IMS will have to perform the procedure after thorough clinical examinations to determine its appropriateness for target patients. This study provided meaningful data on the current state of IMS treatment. We expect that the result of this study will stimulate further more extensive research on IMS.