Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy and a frequent cause of sick leave because of work-related hand overload. The main treatment is operation. Aim: The aim of the study is to assess the usefulness of high frequency ultrasound in the postoperative evaluation of CTS treatment efficacy. Material and methods: Sixty-two patients (50 women and 12 men aged 28–70, mean age 55.2) underwent surgical treatment of CTS. Ultrasound examinations of the wrist in all carpal tunnel sufferers were performed 3 months after the procedure with the use of a high frequency broadband linear array transducer (6–18 MHz, using 18 MHz band) of MyLab 70/Esaote. On the basis of the collected data, the author has performed multiple analyses to confirm the usefulness of ultrasound imaging for postoperative evaluation of CTS treatment efficacy. Results: Among all 62 patients, 3 months after surgical median nerve decompression: in 40 patients, CTS symptoms subsided completely, and sonographic evaluation did not show median nerve entrapment signs; in 9 patients, CTS symptoms persisted or exacerbated, and ultrasound proved nerve compression revealing preserved flexor retinaculum fibers; in 13 patients, scar tissue symptoms occurred, and in 5 of them CTS did not subside completely (although ultrasound showed no signs of compression). Conclusions: Ultrasound imaging with the use of a high frequency transducer is a valuable diagnostic tool for postoperative assessment of CTS treatment efficacy.