Based on the principle of reflected sound waves, ultrasound imaging provides an abstract picture of tissue morphology that may be used to diagnose a wide range of diseases. The nail apparatus contains tissues of various echogenicities, and is thus well suited for ultrasound examination. Moreover, ultrasonography is widely available and is noninvasive, and may therefore be used for longitudinal studies of tissues and diseases. There are methodological limitations in the resolution of ultrasound pictures, but on the other hand, the method allows assessment of functional parameters, such as blood flow. Characteristic ultrasound pictures can be seen in psoriasis, cysts, glomus tumors, and other nail diseases. Furthermore, ultrasound technology allows for the noninvasive examination of trauma and the identification of dislodged nail fragments. Imaging of vasculature may be enhanced by the use of contrast media developed for ultrasonography. Ultrasound examination can contribute significantly to noninvasive examination of the nail apparatus, and may be used to visualize and quantify morphologic and functional aspects of nail biology.