INTRODUCTION/AIMS: Ataxia-telangiectasia (A-T) is a genetic multisystem neurodegenerative disorder characterized by cerebellar ataxia, oculocutaneous telangiectasia, extrapyramidal involvement, peripheral sensorimotor neuropathy, immunodeficiency, pulmonary disease, and an increased risk of malignancy that ultimately determines the shortened lifespan in many patients. A-T nerve ultrasonographic characteristics remain underexplored. This pilot study aimed to characterize the ultrasonographic morphology of peripheral nerves in patients with A-T. METHODS: Ultrasound cross-sectional areas (CSAs) of the median, ulnar, sural, and tibial nerves were obtained from three A-T patients and were compared to reference values. Nerve conduction studies and electromyography were also performed. Given the small sample size and the exploratory nature of this study, formal statistical analyses were not performed, and descriptive statistics were presented for the data. RESULTS: Nerve CSAs in A-T patients were smaller than in healthy controls at all measurement sites. DISCUSSION: Nerve ultrasound revealed atrophy in the peripheral nerves of A-T patients. This reduction in nerve size may distinguish A-T and highlights the utility of nerve ultrasound as a non-invasive diagnostic tool for peripheral sensorimotor neuropathy. These findings may have important implications for early detection in clinical practice.