Pilar sheath acanthoma is a rare benign follicular hamartoma that presents with a central sinus containing keratinous material and is lined by epithelium. It typically occurs on the face, especially on the upper lip and forehead. In our case, the ultrasound (US) feature of pilar sheath acanthoma revealed a well-defined, oval hypoechoic nodule with hypoechoic capping within the dermis over the medial aspect of the calf. To the best of our knowledge, despite many reports on the clinicopathological aspects of pilar sheath acanthoma, this entity has not been well described in the radiologic literature, and US findings have not been documented. We report the US findings of a case of pilar sheath acanthoma on the calf.