The essential provides a systematic overview of the diagnosis and therapy of carpal tunnel syndrome (CTS), the most common compression syndrome of a peripheral nerve. The leading symptom is the "numbness" of the hands. If conservative treatment, preferably with nighttime immobilization of the wrist in a splint, does not lead to lasting relief, an indication arises for open or endoscopic release of the retinaculum. The diagnostic techniques and treatment options are critically discussed and described in detail in accordance with guidelines. Possible risks and complications, as well as the approach for pregnant women, dialysis patients, and others, along with stenosing tenovaginitis as the most important comorbidity, are addressed separately.