Background Although ultrasound imaging is employed ubiquitously today, its use to examine and assess the skin is a relatively new technology. We explored the clinical application and use of high-frequency, high-resolution ultrasound in Mohs micrographic surgery. OBJECTIVE To evaluate the ability of ultrasound to accurately determine lesion length and width of tumor borders in order to reduce the number of surgical stages. METHODS AND MATERIALS This was an institutional review board-approved single-center study of 26 Mohs surgery patients. Ultrasound images were taken to record lesion dimensions, and then the investigator documented clinical estimation of the first stage. Extirpation of the tumor and histological analysis were performed thereafter. RESULTS The results of 20 patients were included in the analysis. A paired-samples t-test revealed no significant difference between clinical and ultrasound widths (t=-1.324, p=.20). Similarly, there was no significant difference between the lengths found from clinical assessment and ultrasound (t=-1.093, p=.29). For different tumor types, there was no significant difference between clinical and ultrasound widths or lengths for basal cell carcinoma (t=-1.307, p=.23; t=-1.389, p=.20) or squamous cell cancer (t=-0.342, p=.73; t=0.427, p=.68). CONCLUSION There is a diagnostic role for high-resolution ultrasound in Mohs surgery regarding the delineation of surgical margins, but its limitations preclude its practical adoption at this time. The ultrasound equipment was loaned to the investigators.