In 1994, it was estimated that about 44,500 American women would die from breast cancer and 7000 women from cervical cancer. While early detection methods (screening mammography, breast examinations, and pap smears) have proven to be effective means of decreasing these cancers, they are underused by all groups. In particular, low-income women use them least, resulting in their lower survival and higher mortality rates than the rest of the population. This article quantifies the effect of a simple intervention undertaken by a health maintenance organization (HMO) serving the indigent to improve breast and cervical cancer screening rates. The HMO mailed personal letters and newsletter articles to women members > or = 40 years about the need for cancer prevention. Articles also were printed in the monthly HMO newsletters to providers about the benefits of using these early detection methods. A review of provider claims from 574 women showed that baseline utilization rates for screening mammograms and pap smears before the intervention in year 1 (1990) were 14% and 16.4%, respectively. After the intervention, in years 2 and 3, mammograms had increased to 41% and pap smears to 38% for both years, indicating a levelling off effect of the intervention by year 3. These data show that while a significant improvement in screening behaviors was achieved, the intervention impact was limited to only about one third of the sample on the long term. Further, data do not indicate whether behavioral change was initiated as the member or provider level. More research is needed to increase overall screening behavior among the indigent and their physicians. The results reported here provide a baseline against which more intensive interventions can be measured in this setting.