Self-poisoning in adults is an important public health problem across the world, but evidence to guide psychological management is lacking. In the current cohort study we wished to investigate whether aspects of routine Emergency Department management such as receiving a psycho-social assessment, or being referred for specialist follow up, affected the rate of repetition of self-poisoning. The study was carried out in four inner city hospitals in Greater Manchester, United Kingdom, over a 5-month period. We used hospital information systems and reviewed the case notes of every patient presenting to the Emergency Department to identify prospectively all adult patients presenting with deliberate self-poisoning. Data regarding the Emergency Department management of each episode were collected. The Manchester and Salford self-harm database was used to determine the number of individuals who went on to repeat self-poisoning within 6 months of their index episode. During the recruitment period 658 individuals presented with self-poisoning. Traditional risk factors for repetition such as substance dependence, psychiatric contact, and previous self-poisoning were associated with a greater likelihood of receiving a psycho-social assessment or being referred for specialist follow-up. Ninety-six patients (14.6%) repeated self-poisoning within 6 months of their index episode. After adjustment for baseline demographic and clinical characteristics and hospital, receiving a psycho-social assessment was not associated with reduced repetition but being referred for specialist follow-up was [adjusted hazard ratio for repetition (95% CI): 0.49 (0.25 to 0.84), P=.01]. We found that being referred for active follow-up after self-poisoning was associated with a reduced risk of repetition. The implications of this finding are discussed. Further studies using both cohort and randomized controlled study designs will help inform management strategies for patients who poison themselves.