The scenario is all too familiar. A patient has a surgical procedure. Anesthesia is uneventful and the procedure goes well. Nothing untoward is observed in the recovery room. Later that evening the patient complains of numbness, weakness, or pain, and a neurological deficit is found. A neurologist is called, examines the patient, and it is concluded that a nerve lesion has occurred, because of stretch, ischemia, compression, or laceration. A subsequent electromyogram and nerve conduction study confirm the clinical impression, but offer little in the way of explanation. Over the subsequent months, the patient makes a slow recovery but there has been a prolonged period of pain and disability. Liability issues loom. This scenario could reflect a number of different nerve lesions. This review illustrates the different modes of pathogenesis that may occur and the variable nature of the neurological deficits. We grouped these lesions according to the clinical setting in which they occur.