Post-stroke spasticity is a common complication that causes limitations of function, pain and decrement of the quality of life. Although botulinum toxin injection and anti-spastic medications are effective and widely used for the management of post-stroke spasticity, clinical applications are often limited in stroke patients because of their invasiveness and systemic side effects. Alternatively, we performed upper limb muscle-belly extracorporeal shock wave therapy (ESWT) to resolve problematic spasticity in two subacute stroke patients. Serial quantitative ultrasonographic measurements of spastic muscle were conducted to investigate the rheological changes in chronological order by echogenicity comparison. After 4 sessions of weekly ESWT, gradual decrements of clinical spasticity parameters and muscle echogenicity were observed and lasted for 1 week after the cessation of the therapy. ESWT may be a useful alternative management for treating post-stroke spasticity.