Carpal tunnel syndrome, the most common entrapment neuropathy of the upper extremity, is caused by compression of the median nerve as it travels through the carpal tunnel. Classically, patients with the condition experience pain and paresthesias in the distribution of the median nerve, which includes the palmar aspect of the thumb, index and middle fingers, and radial half of the ring finger. Additional clues include positive physical examination findings, such as the flick sign, Phalen maneuver, and median nerve compression test. Although patients with typical symptoms and signs of carpal tunnel syndrome do not need additional testing, ultrasonography and electrodiagnostic studies are useful to confirm the diagnosis in atypical cases and rule out other causes. If surgical decompression is planned, electrodiagnostic studies should be obtained to determine severity and surgical prognosis. Conservative treatment may be offered initially to patients with mild to moderate carpal tunnel syndrome. Options include splinting, corticosteroids, physical therapy, therapeutic ultrasound, and yoga. Nonsteroidal anti-inflammatory drugs, diuretics, and vitamin B6 are not effective therapies. Local corticosteroid injection can provide relief for more than one month and delay the need for surgery at one year. Patients with severe carpal tunnel syndrome or whose symptoms have not improved after four to six months of conservative therapy should be offered surgical decompression. Endoscopic and open techniques are equally effective, but patients return to work an average of one week earlier with endoscopic repair.