We systematically reviewed observational studies investigating ultrasound elastography for median nerves in the carpal tunnel syndrome (CTS) population. PubMed and Embase were studied from the earliest record to April 2019. The primary outcome was the comparison of elasticity of the median nerve between participants with and without CTS, quantified by the standardized mean difference (SMD) and its 95% confidence interval. The median nerve is considered to be stiffer in the CTS population when the SMD of tissue strain is negative, or that of strain ratio, shear modulus and shear wave velocity are positive. The present meta-analysis included 17 studies, evaluating 1401 wrists. Our result showed that regardless of the ultrasound elastography mode (tissue strain, strain ratio, shear modulus and shear wave velocity) used, median nerves at the wrist level in patients with CTS were consistently stiffer than those in healthy controls. Importantly, ultrasound elastography revealed its potential in differentiating CTS of different severity. (C) 2019 World Federation for Ultrasound in Medicine & Biology. All rights reserved.