Trends in deliberate self-harm (DSH) are important because they have implications for hospital services, may indicate levels of psychopathology in the community and future trends in suicide, and can assist in identification of means of suicide prevention. We have investigated trends in DSH and characteristics of DSH patients between 1990 and 2000 based on data collected through the Oxford Monitoring System for Attempted Suicide. During the 11-year study period 8590 individuals presented following 13858 DSH episodes. The annual numbers of persons and episodes increased overall by 36.3% and 63.1% respectively. Rates (Oxford City) declined, however, in the final 3 years. There were gender- and age-specific changes, with a rise in DSH rates in males aged > or = 55 years and in females overall and those aged 15-24 years and 35-54 years. Repetition of DSH increased markedly during the study period. Antidepressant overdoses, especially of SSRIs, increased substantially. Paracetamol overdoses declined towards the end of the study period. Alcohol abuse, use of alcohol in association with DSH, and violence increased, especially in females, and the proportion of patients in current psychiatric care and misusing drugs also rose. While overall rates of DSH did not increase markedly between 1990 and 2000, substantial changes in the characteristics of the DSH population and a rise in repetition suggest that the challenges facing clinical services in the management of DSH patients have grown.