The objective was to determine the pattern of repeated deliberate self harm (DSH) in a busy inner-city teaching hospital. We undertook a retrospective cohort analytical study for all 1,576 DSH patients seen for assessment over a two-year period. Age, sex and previous DSH were noted at index episode (562 (36%) reported a previous history). Each patient was followed up for 12 months and repetition of DSH was recorded. DSH was repeated by 193 (12%) within one year, 138 (72%) once and 55 (28%) more than once. Repetition was more common and occurred much more quickly in those with a previous history than those without (relative risk: 3.4). Median time to repetition was 12 weeks but about 10% repeated within a week. The results were similar for men and women. This implies that previous history is the single most useful predictor in the repetition of DSH. Repetition occurs quickly and most rapidly in those who have previously harmed themselves. Intervention aimed at reducing repetition of self harm must be delivered within days, not weeks.