Thanks to ultrasound (US) has a low cost, portable, available and non-invasive, the use of diagnostic US in musculoskeletal diseases is rapidly growing in worldwide. Because it is easy to identify the limb structures such as muscle, tendon, and nerves and also, their pathologies, US is frequently used by physiatrists, orthopedics, rheumatologists, sports medicine and pain management physicians nowadays. Providing images of the median nerve (MN) and accompanying structures and give dynamic images about the anatomy of the carpal tunnel are the most superiorities of US in carpal tunnel syndrome (CTS) diagnosis. The diagnose of CTS based on history and physical examination and confirmed with electrodiagnostic studies. Although the specificity of nerve conduction tests is high, there is significant variability in sensitivity (62-85%). Therefore, US has been suggested as an additional or alternative diagnose of CTS. Especially measurement of the cross-sectional area (CSA) of the MN is significantly greater in CTS patients and shows a significant correlation with electrodiagnostic findings such as sensory nerve conduction velocity (SCV) and distal motor latency (DML). Because it enhances the diagnostic accuracy the detection of the epineural or intraneuronal blood flow, the three techniques of Doppler US, are more recently preferred. The contributions of color, power and spectral Doppler techniques in CTS diagnosis, were studied in various studies before. While for the detection of intraneural flow, the power Doppler (PD) seems to be the best way, the specify, sensitivity and diagnostic accuracy of each Doppler techniques were good in most studies.