The purpose of this study was to investigate the effect of ultrasound (US) on the spasticity occurring in the ankle plantar flexor muscles after a cerebrovascular event. According to the modified Ashworth scale (MAS), the hemiplegic patients with stage 2-3 spasticity on the ankle plantar flexor muscles were enrolled in the study and divided into two groups. Passive stretching exercise was applied to both groups. Additionally, 10-minute US was applied to one of the groups, using the mode of continuous wave of 1.5w/cm 2 to the calf muscles before stretching. In order to monitor the efficacy of the treatment in the patients, MAS, Hmax/Mmax ratio, the ankle range of motion (ROM), Functional Independence Measure and Brunnstrom Motor Recovery Stage were evaluated. While a significant recovery was monitored in the MAS and ankle ROM measurements after treatment in both groups, no change was obtained in the other parameters. No significant difference was detected in any of the measurements between the groups. In this study, US treatment applied in combination with the ankle plantar flexor muscles passive stretching exercise was determined to have no effect on the stretching treatment in minimizing the spasticity.