Tricyclic antidepressant overdose is a frequent diagnosis in the emergency room. It is responsible for a significant percentage of hospital admissions for observation and treatment. This is due to its cardiac (as well as neurologic) toxicity, and the difficulty in predicting its clinical gravity. The authors present the paper with two objectives in mind: 1) information about a common and significant cardiological emergency; 2) presentation of the methodology concerning systematic reviews of the literature. In this first (of four) articles, the epidemiology tricyclic antidepressant overdose is presented. In the remaining three papers we will present its clinical presentation, diagnosis, treatment, prognosis and prevention. Note: this is the first of a series of four articles on the cardiac toxicity of tricyclic antidepressant overdose; the next three articles will be presented in the July, August and September issues of the RPC.