This study assessed the cost-effectiveness of cervix and breast cancer screening in a public hospital emergency room. Age-eligible women with nonurgent conditions and without recent screening were offered screening by a nurse. A decision analysis compared the costs and outcomes of emergency room screening and standard hospital screening efforts. The undiscounted cost-effectiveness results for establishing new programs were $4050 (cervical cancer), $403,203 (breast cancer), and $4375 (joint cervix and breast cancer) per year of life saved. If screening is added to an existing program, results are more favorable ($429, $21,324, and $479 per year of life saved for cervix, breast, and joint screening, respectively). Results were most sensitive to volume and probability of receiving treatment after an abnormal screen. Emergency room screening was cost-effective for cervical cancer; breast cancer screening was relatively expensive given the low number of women reached. More intensive recruitment and follow-up strategies are needed to maximize the cost-effectiveness of such programs.