Reduction in medical care utilization is one criteria for assessing the impact of mental health treatment for children with psychosocial problems. This reduction has been termed the "offset" effect. Almost all published research concerning offset after mental health treatment concerns adults, and the few studies in pediatric populations are limited by methodologic problems. A study of health care utilization after mental health treatment for children was conducted. Mental health treatment for psychosocial problems was significantly associated with decreased use of medical care only for older children, after potentially confounding variables were controlled for. Furthermore, this decreased use was found only for nonmental health specialty care visits. No reduction in primary care visits occurred. Other factors such as previous patterns of use and the presence of other morbidity were stronger predictors of subsequent primary health care use than was mental health treatment. Mental health treatment does not have a major impact on the high utilization of most children with psychosocial problems in pediatric settings. Because the reasons for this may be particular morbidity patterns in these children, future studies should include some measure of case mix as a potentially important variable in assessment of mental health treatment effects.