Purpose: The purpose of this study were to analyze ultrasonography on both sides of gastrocnemius medialis of stroke patient. Methods: In fourteen subjects with stroke, the gastrocnemius medialis(GM) muscle were scanned with ultrasonography at the muscle belly at rest at ankle angles of 0 degree (neutral position) and it were measured with ultrasonography on both sides of the leg. Muscle architecture (thickness, pennation angle, fascicle length, density, white area index) was examined using real-time B-mode ultrasonography with 7.5MHz linear-array prob. Results: Thickness of non-paratic side was significantly thicker than paratic side. Pennation angle of non-paratic side was significantly larger than paratic side. Fascicle length of non-para tic side was significantly smaller than paratic side. Density of non-paratic side was significantly smaller than paratic side. White area index of non-paranc side was significantly smaller than paratic side. Conclusion: This study showed that stroke have influenced on mechanical properties and quality properties of skeletal muscle architecture.