A prospective, randomized, controlled trial of self-care educational interventions was conducted in a health maintenance organization to determine their effect on ambulatory care utilization. Statistically significant decreases in total medical visits and minor illness visits were found in each of three experimental groups as compared with a control group. These decreases averaged 17% and 35%, respectively. These results were most clearly linked to a system of written communications emphasizing personal decision making about the use of medical care. The addition of a nurse counseling session to the written materials may increase cost savings and appears to be attractive to "high utilizers." A telephone information service was offered but not used. It is estimated that the decreases in utilization could result in a savings of approximately $2.50 to $3.50 for each dollar spent on the educational interventions. Self-care education systems may have important effects on medical care costs, physician satisfaction, and patient confidence.