The three syndromes described in this article were chosen from about a dozen nerve-compression disorders that affect the arm from scapula to digits. They illustrate the range of problems encountered. None of the other syndromes are as common, and in some instances (pronator syndrome and anterior interosseous syndrome), localized inflammation is at least as common a cause of neuropathy as is compression. Some syndromes of nerve compression have important implications for musicians, athletes, and those who place stress on the upper limbs through heavy or repeated use. Well-designed prospective trials are clearly needed to expand our knowledge of the prevention and treatment of the entrapment neuropathies. Much more needs to be known about the long-term natural history of these disorders, since prevention is usually possible.