Primary care physicians may mistakenly conclude that sexual issues are unimportant to divorced or widowed mature women, based on age and gender biases. Although research suggests that many single mature women are sexually active, physicians are often reluctant to discuss sexual matters with them. Structured and open-ended interviews explored perceptions regarding mature women's sexuality and HIV-related risk for patient-physician communication among 44 'recently single' mature women aged 45-68 and 31 primary care physicians. Age and ethnic group comparisons with the mature women suggest that younger and African-American women reported higher HIV and STI risk perception than older and White women. Many mature women (64%) believed that they were at-risk for HIV and STIs, whereas physicians considered younger patients most at-risk and that risk declined with patients' advancing age and with female status. Mature women and physicians had different expectations regarding initiation of clinical sexual health discussions, with 44% of the mature women placing the onus of responsibility on the patient, whereas 74% of physicians believed it was the role of both doctors and patients to bring up these topics. The findings are instructive to primary care physicians and healthcare policy makers, indicating that sexual health issues are relevant to mature women's continued health and well-being.