OBJECTIVE: To compare the effect of individual educational visits versus group visits using academic detailing to discuss prescribing of highly anticholinergic antidepressants in elderly people. DESIGN: Randomised controlled trial with three arms (individual visits, group visits, and a control arm). SETTING: Southwest Netherlands. PARTICIPANTS: 190 general practitioners and 37 pharmacists organised in 21 peer review groups were studied using a database covering all prescriptions to people covered by national health insurance in the area (about 240 000). INTERVENTION: All general practitioners and pharmacists in both intervention arms were offered two educational visits. For physicians in groups randomised to the individual visit arm, 43 of 70 general practitioners participated; in the group visit intervention arm, five of seven groups (41 of 52 general practitioners) participated. MAIN OUTCOME MEASURES: Numbers of elderly people (>/=60 years) with new prescriptions of highly anticholinergic antidepressants and less anticholinergic antidepressants. RESULTS: An intention to treat analysis found a 26% reduction in the rate of starting highly anticholinergic antidepressants in elderly people (95% confidence interval -4% to 48%) in the individual intervention arm and 45% (8% to 67%) in the group intervention arm. The use of less anticholinergic antidepressants increased by 40% (6% to 83%) in the individual intervention arm and 29% (-7% to 79%) in the group intervention arm. CONCLUSIONS: Both the individual and the group visits decreased the use of highly anticholinergic antidepressants and increased the use of less anticholinergic antidepressant in elderly people. These approaches are practical means to improve prescribing by continuing medical education.