According to the aesthetic standards of Asians, having large calves is considered a hindrance to lower leg beauty. Botulinum toxin type A (BoNT-A), functioning as a synaptic junction blocker to reduce muscle contraction, is widely used to treat muscle hypertrophy, and its efficacy has been demonstrated by previous studies in young Asians. 1 Different from small-size muscles like masseter, gastrocnemius muscle (GM) is a relatively large muscle that is difficult to be totally covered by BoNT-A. To obtain a better outcome, multiple injection protocols have been executed and revised by different researchers to paralyze gastrocnemius muscle as evenly as possible. This requires a profound knowledge of the morphology of gastrocnemius muscle. [2][3][4] However, our major perception of the gastrocnemius muscle mainly originated from cadaveric anatomical data. The anatomical information in the living body remains unknown. B-mode ultrasound imaging is a cost-effective method to acquire real-time visualization of a patient's anatomical structure, which has been used to access the effectiveness of BoNT-A injection by measuring muscle thickness change. [4][5][6] Yet, the specific baseline data is rarely disclosed in detail. This study, therefore, applies ultrasonography intending to