To investigate the effect of radial extracorporeal shock wave therapy (rESWT) on hemiplegic shoulder pain (HSP) syndrome.In this monocentric, randomized, patient-assessor blinded, placebo-controlled trial, patients with HSP were randomly divided into the rESWT (n=17) and control (n=17) groups. Treatment was administered four times a week for 2 weeks. The visual analogue scale (VAS) score and Constant-Murley score (CS) were assessed before and after treatment, and at 2 and 4 weeks. The Modified Ashworth Scale and Fugl-Meyer Assessment scores and range of motion of the shoulder were also assessed.VAS scores improved post-intervention and at the 2-week and 4-week follow-up in the intervention group (p<0.05). Respective differences in VAS scores between baseline and post-intervention in the intervention and control groups were -1.69±1.90 and -0.45±0.79, respectively (p<0.05), between baseline and 2-week follow-up in the intervention and control groups were -1.60±1.74 and -0.34±0.70, respectively (p<0.05), and between baseline and 4-week follow-up in the intervention and control groups were -1.61±1.73 and -0.33±0.71, respectively (p<0.05). Baseline CS improved from 19.12±11.02 to 20.88±10.37 post-intervention and to 20.41±10.82 at the 2-week follow-up only in the intervention group (p<0.05).rESWT consisting of eight sessions could be one of the effective and safe modalities for pain management in people with HSP. Further studies are needed to generalize and support these results in patients with HSP and a variety conditions, and to understand the mechanism of rESWT for treating HSP.