Objective: The repeated, self-inflicted, non-accidental injury known as Self Injurious Behaviour (SIB) is a cause of severe stress to carers and a challenge to multi-disciplinary teams working with people with a mental handicap. A need for Irish data on this problem was answered by collecting a representative cohort and following its members up to record the prevalence of SIB.

Method: The group studied included all people with an IQ of less than 50 (that is those in the moderate, profound and severe range of intellectual ability) whose place of origin was within the geographical borders of a single community care area. Following a preliminary tracing process, each person was followed up for one calendar month using a specifically prepared format to record daily occurrence of SIB.

Results: The group resulting from the tracing process consisted of 429 people (= 0.4% of the total population), 62 (=14 %) of this group exhibited SIB, during the time of the study. Of the demographic variables studied SIB was found to be related to IQ. Of those who self-injured those who showed multiple topographies and those who showed the greatest frequency of SIB were more likely to be found in the population who lived in a residential facility.

Conclusions: SIB is related to IQ but in a non-linear way suggesting that factors other than IQ militate against more severely handicapped people displaying this behaviour. SIB is not caused by living in a residential centre however our results suggest that living in a residential facility is the result of displaying SIB. This study suggests that implications for future treatment approaches and service provision for those exhibiting SIB in Ireland can be made with reference to research from other countries.