OBJECTIVE: To evaluate the impact of regular multidisciplinary team interventions on the quantity and quality of psychotropic drug prescribing in Swedish nursing homes. DESIGN: A randomized controlled trial. SETTING: A sample of 33 nursing homes: 15 experimental homes and 18 control homes representing 5% of all Swedish nursing homes. PARTICIPANTS: The sample consisted of 1854 long-term care residents with an average age of 83 years. Seventy percent of the residents were women, and 42% had a documented diagnosis of dementia. An additional 5% had a psychotic disorder, and 7% had a diagnosis of depression. INTERVENTION: Experimental homes participated in an outreach program that was designed to influence drug use through improved teamwork among physicians, pharmacists, nurses, and nurses' assistants. Multidisciplinary team meetings were held on a regular basis throughout the 12-month study period. MEASUREMENTS: Lists of each resident's prescriptions were collected 1 month before and 1 month after the 12-month intervention. Measures included the proportion of residents with any psychotropic drug, polymedicine, and therapeutic duplication and proportion of residents with nonrecommended and acceptable drugs in each psychotropic drug class, as defined by current Swedish guidelines. RESULTS: Baseline results show extensive psychotropic drug prescribing, with the most commonly prescribed drugs being hypnotics (40%), anxiolytics (40%), and antipsychotics (38%). After 12 months of team meetings in the experimental homes, there was a significant decrease in the prescribing of psychotics (-19%), benzodiazepine hypnotics (-37%), and antidepressants (-59%). Orders for more acceptable antidepressants also increased in the experimental homes. In the control homes there was increased use of acceptable antidepressants, but there were no significant reductions in other drug classes. CONCLUSIONS: There is excessive prescription of psychotropic drugs in Swedish nursing homes. Improved teamwork among caregivers can improve prescribing as defined by clinical guidelines.