The objective of this chapter is to introduce the entrapment neuropathy in the upper extremity. Entrapment neuropathy is essentially an injury cases by unphysiological compression of a peripheral nerve. To understand the pathophysiology, we should briefly recapitulate the vascular anatomy. Various nerves undergo entrapment neuropathies at various sites. Some of the more common and clinically relevant compression neuropathies have been discussed here in this chapter. Anterior interosseous nerve syndrome is caused due to entrapment of AIN by tendinous origin of the deep head of the pronator teres, other variant tendinous structures, fibrous bands, or collateral vessels. Spontaneous and traumatic causes have also been well described. Causes of entrapment, clinical features of entrapment, diagnosis and treatment of entrapment are also discussed in this chapter.