A systematic search of seven electronic databases was done to identify randomized controlled trials that assessed the effect of computer-generated patient education material (PEM) on professional practice. Three studies met the authors' criteria. All three studies involved preventive care. All used a complex intervention of which computer-generated PEM was a major component. Improvements in practice were seen in all studies, although these gains were generally modest. One study showed improvement in patient outcomes. Mann-Whitney statistics calculated for the studies' outcome measures ranged from 0.48 to 0.66, equivalent to risk differences of -4 to 32 percent. Computer-generated PEM seems to have a small, positive effect on professional practice. The small number of included studies and the complex nature of the interventions makes it difficult to draw conclusions about the ability of computer-generated PEM to change professional practice. Future work should involve well-defined interventions that can be clearly evaluated in terms of effect and cost.