Anesthesiologists need to be aware of the use of illicit drugs because of the long-term negative consequences that it may have on health and how it impacts on anesthetic care, knowledge of a patient substances abuse postoperatively may prevent adverse drug interactions, predicts tolerance to anesthetic agents and facilitate the recognition of drug withdrawal, therefore it is important for anesthesiologists to know about the most common illicit drugs being used, to know their side effects and their clinical presentation if abused or intoxicated, and to know what anesthetic options would be the most beneficial.