This paper examines how consistently hospital separation E-code data reflect suicidal behaviours. Expert clinicians reviewed medical records of individuals who had a separation for self-poisoning to determine whether the self-poisoning was deliberate. A summary estimate of the prevalence of deliberate self-poisoning was derived, which was then compared to the prevalence of deliberate self-poisoning based on the external cause of injury (E-Codes). Large discrepancies were found among older age groups. (53 refs)