Concern over rising healthcare expenditures has led to increased scrutiny of medical practices. As medical liability and malpractice risk rise to crisis levels, the medical-legal environment has contributed to the practice of defensive medicine as practitioners attempt to mitigate liability risk. High-risk specialties, such as neurosurgery, are particularly affected and neurosurgeons have altered their practices to lessen medical-legal risk. We present the first national survey of American neurosurgeons' perceptions of malpractice liability and defensive medicine practices. A validated, 51-question online-survey was sent to 3344 practicing U.S. neurosurgeon members of the American Association of Neurological Surgeons, which represents 76% of neurosurgeons in academic and private practices. A total of 1028 surveys were completed (31% response rate) by neurosurgeons representing diverse sub-specialty practices. Respondents engaged in defensive medicine practices by ordering additional imaging studies (72%), laboratory tests (67%), referring patients to consultants (66%), or prescribing medications (40%). Malpractice premiums were considered a "major or extreme" burden by 64% of respondents which resulted in 45% of respondents eliminating high-risk procedures from their practice due to liability concerns. Concerns and perceptions about medical liability lead practitioners to practice defensive medicine. As a result, diagnostic testing, consultations and imaging studies are ordered to satisfy a perceived legal risk, resulting in higher healthcare expenditures. To minimize malpractice risk, some neurosurgeons have eliminated high-risk procedures. Left unchecked, concerns over medical liability will further defensive medicine practices, limit patient access to care, and increase the cost of healthcare delivery in the United States.