The purpose of this meta-analysis was to assess the effects of extracorporeal shock wave therapy (ESWT) on reducing spasticity immediately and 4 weeks after application of ESWT. [Subjects and Methods] We searched PubMed, TCL, Embase, and Scopus from their inception dates through June 2013. The key words “muscle hypertonia OR spasticity” were used for spasticity, and the key words “shock wave OR ESWT” were used for ESWT. Five studies were ultimately included in the meta-analysis. [Results] The Modified Ashworth Scale (MAS) grade was significantly improved immediately after ESWT compared with the baseline values (standardized mean difference [SMD], −0.792; 95% confidence interval [CI], −1.001 to −0.583). The MAS grade at four weeks after ESWT was also significantly improved compared with the baseline values (SMD, −0.735; 95% CI, −0.951 to −0.519). [Conclusion] ESWT has a significant effect on improving spasticity. Further standardization of treatment protocols including treatment intervals and intensities needs to be established and long-term follow up studies are needed.