The National Cancer Institute of the United States has set a goal for the year 2000 that 80-90% of eligible women should have a Pap smear every 3 years and that 80% of women aged 50-70 should receive an annual breast examination and mammogram. Very few studies have examined how we might best measure our progress towards this goal. Specifically, should we employ interview data or data derived from medical records? To respond to this question, data were gathered at two different public health clinics in poor areas of Chicago using both techniques. The interviews estimated significantly higher proportions of women receiving Pap smears, breast examinations, and mammograms in the previous 12-month interval than were estimated from randomly selected medical records. A review of the literature suggests the same pattern exists when other studies using these two data gathering processes are compared. We are thus left with a serious problem, one that must be resolved before we will be able to fully assess our progress in increasing breast and cervical cancer screening.