Objective. To determine if whole body vibration therapy (WBV) effectively improves functional outcome in patients with poststroke hemiplegia. Materials and Methods. In this single-blind RCT, WBV group (n = 10) had 40 hz frequency/4 mm amplitude vibration during 5 minutes/session, 3 days a week, for a duration of 4 weeks. The control group (n = 11) had no vibration therapy for the same duration while standing on the same platform. Patients in both of the groups did 15 minutes of stretching and active range of motion exercises before the intervention. Outcome measures were Modified Ashworth Scale (MAS), Functional Independence Measurement (FIM), and Timed 10-Meter Walk Test (10 mWT). Results. Only 10 mWT improved at the 1st week (p = 0.002), 1st month (p < 0.001), and 3rd month (p < 0.001) in favor of the intervention group. There was positive correlation also between 10 mWT and ankle spasticity (p < 0.001, r = 0.931). Conclusion. This study suggests that WBV therapy may be a complementary therapy in gait rehabilitation and functional outcome of the patients with calf muscle spasticity.