Background: Although research is starting to identify those factors that predict contact with mental health services in individuals with intellectual disabilities, very little is known about the patterns of service use following referral. Yet, this information is vital for effective service planning and development. We therefore examined the factors associated with service consumption. Methods: We constructed a service consumption index based on the number of outpatient clinics attended, contacts with the community psychiatric nurses, home visits by a psychiatrist and the number of admissions. This consumption index was used to divide the sample (n = 115) into two groups: heavy and light service users. Results and conclusions: Logistic regression analysis indicated that, after controlling for the length of service contact, individuals with a diagnosis of schizophrenia spectrum disorder and those with a greater number of affective/neurotic symptoms were more likely to be heavy service users. Age, living situation and the degree of intellectual disabilities were not found to be significant predictors of service consumption. The results also suggest that a small proportion of service users consumed almost half of the service resources.