Carpal tunnel syndrome (CTS) is caused by compression of the median nerve as it travels through the carpal tunnel. Patients commonly experience pain, paresthesia, and, less often, weakness in the distribution of the median nerve. Provocative maneuvers, such as the Phalen test and Tinel sign, have varying sensitivity and specificity for the diagnosis of CTS. Thenar atrophy is a late finding and highly specific for CTS. Although patients with a classic presentation of CTS do not need additional testing for diagnosis, electrodiagnostic studies can confirm the diagnosis in atypical cases, exclude other causes, and gauge severity for surgical prognosis. An abnormal nerve conduction study is useful for ruling in CTS, but a normal test does not necessarily exclude it. Over-the-counter analgesics, such as nonsteroidal anti-inflammatory drugs and acetaminophen, have not shown benefit for CTS. Patients with mild to moderate CTS initially may be offered nonsurgical treatments, such as splinting or local corticosteroid injections. Night-only splinting is as effective as continuous wear. A neutral wrist splint may be more effective than an extension splint. In patients with recent onset of CTS, corticosteroid injections provide slightly greater improvement of symptoms compared with splinting at 6 weeks, with similar outcomes at 6 months. Patients with severe CTS, including objective weakness or sensory deficits, should be offered surgical decompression. Endoscopic and open carpal tunnel release techniques are equally effective.