The authors start with definitions and classification of a depressed conscious state and proceed to detail practical tips in the initial assessment of patients with coma, focussing on the history and examination. They impress the number of non-neurological causes of coma, which may need to be considered. The assessment of pupillary responses, eye movement abnormalities and abnormal breathing patterns are described. They also explore the utility of basic initial investigations, including blood gases and briefly discuss specialist neuro-imaging and electroencephalography.