Substance abuse is of global public health concern. The United Nations Office on Drug and Crime in Nigeria indicates that 14.4% (14.3 million) of people aged between 15-64 years abuse drugs. This is of particular concern to the anaesthetist as illicit drug use has multi systemic effects which if not properly managed can jeopardize the chances of a successful surgery or critical care. Anaesthetists come into contact with patients who are under the influence of these drugs for various indications. They can present for elective/emergency surgeries, they could present in situations requiring basic and advanced life support due to complications from their life styles, or from other critical situations such as road traffic accidents requiring intensive care. The aim of anaesthesia is to determine the possible effects of illicit drug use on the various body systems, determine the presence and extent of complications due to illicit drug use, to optimize the patient as much as possible prior to sugery and to choose an anaesthetic technique with the least detrimental effect on the patients’ condition. All these will aid the anaesthetic team to develop a safe care plan for the successful management of this category of patients.