BACKGROUND Screening for breast and cervical cancer reduces disease-specific mortality, but high rates of comorbidity and disability among elderly persons may alter the risks and benefits of screening. METHODS We performed a mail survey of primary care physicians to estimate the impact of health status on physicians' intentions to offer cancer screening to older women. Respondents were asked to read a scenario about an older woman. Each scenario patient was one of three ages (70, 80, or 90) and had one of three levels of comorbidity and disability. Respondents were asked to estimate the likelihood of offering screening with mammography and Pap smear to these patients on a 5-point Likert scale. A logistic regression compared those physicians somewhat or very likely to offer screening with those less likely to do so. Further analyses examined the characteristics of physicians likely to "overscreen" the frailest older women (<5 years median life expectancy) or "underscreen" the healthiest (>10 years median life expectancy). RESULTS Respondents returned 2003 completed surveys (37.4%). Controlling for age and prior screening, higher levels of comorbidity and disability were associated with a significantly lower likelihood of offering screening for both mammography and Pap smear. Nonetheless, a substantial percentage (30.7%) of physicians indicated a high likelihood of offering a frail 90-year-old woman a mammogram, and 13.4% would offer her a Pap smear. In general, overscreening was more common than underscreening. Female gender was associated with "overscreening" with mammography, whereas male gender and lack of board certification predicted "underscreening." Lack of board certification was associated with "overscreening" with Pap smear. CONCLUSIONS In addition to age, primary care physicians consider health status in deciding to offer cancer screening to older women. Education and guidelines for cancer screening should more explicitly address the risks of overscreening among frail older women.