Since the implementation of a psychiatric service in a long-term facility for people with intellectual disability, the usage of psychotropic and anti-convulsant drugs has been surveyed over the 5-year period 1994-1999. At that time, although the overall prevalence rate of residents on medication was not declining significantly, a decrease in number, dosage and polypharmacy of those receiving neuroleptic drugs occurred than 1994. A reduction also resulted among the in-patients prescribed anxiolytic preparations, despite a relative increase in their mean daily intake. Anti-convulsant drugs climbed slightly during the same interval with a parallel increase in the mean daily dosage. A retrospective comparison of current findings to prevalence, dosage and type of psychoactive medications dispensed 10 years previously in 1989 revealed no trend towards drug rationalisation. Until interdisciplinary training programmes as well as effective community services combining disability and mental health needs are forthcoming, a therapeutic approach involving early psychiatric inputs may contribute to ensure a more rational prescribing practice for long-stay adults with intellectual disability who are referred for neuro-psychiatric consultation.