Background: Self-injurious behaviour (SIB) is a relatively common problem for people with intellectual disabilities and it is known to be associated with various risk markers, such as degree of disability, sensory impairments, and autism (McClintock "et al." 2003). Less is known about its long-term course however. Method: The present study was conducted to examine the quality of life and changes in behaviour for a cohort of 49 people with intellectual disabilities and SIB who were all part of a previous total population study conducted in the south of England by Oliver, Murphy and Corbett (1987). Assessment tools used in the original study, and an additional quality of life measure, the Life Experience Checklist (Ager, 1990), were carried out with informants in the participant's homes or places of day activity. Results: The results show that 84% of the sample continued to self-injure nearly 20 years on, with no significant mean changes in number of topographies or severity of SIB across the group. No one was living in hospital in this study (cf. many individuals in the first survey) but for those who had moved out of hospital, their SIB had not reduced. More people were receiving psychological treatment; more were also receiving anti-convulsant and anti-psychotic medications, though polypharmacy had reduced somewhat. The number of people accessing full-time day activities had decreased substantially, with 44% of people only accessing structured daily activities for 2 1/2 days per week or less. Conclusions: The results of the study add to the growing evidence of extreme chronicity for SIB and the relative lack of impact of treatment for people in whom self-injury has become well-established. They imply that early intervention is essential if such behaviour is to be eliminated long term.