Prevalence rates of psychotropic drug use in people with intellectual disabilities are high and pharmacotherapy is often attempted with multiple drugs. The presence of disruptive behavior is an important factor associated with the use of psychotropic drugs in this population. We wanted to gain insight into prevalence and determinants of multiple psychotropic drug use among patients with mild intellectual disabilities or borderline intellectual functioning with psychiatric or behavioral disorders. Therefore, data on psychotropics and possible determinants of use were retrospectively collected during 1992-1997 in a specialized closed ward of a Dutch general psychiatric hospital. We defined multiple drug use as concomitant prescription (regular or as needed) of a combination of benzodiazepines/tranquilizers/antipsychotics/anticonvulsants/anti-depressants. Multiple drug use, seen in 48% of the patients, was associated with a long duration of stay, psychosis, aggressive, bizarre, attention-seeking behavior and involuntary measures. We conclude that it is likely that difficulties in the management of socially disruptive behavior are often countered by multiple drug prescription.