BACKGROUND: Many women use complementary and alternative medicine (CAM). Although CAM use has been associated with reductions in conventionally recommended pediatric preventive care (e.g., vaccination), little is known about associations between CAM use and receipt of recommended preventive screening in women. METHODS: Using Washington State insurance data from 2000 to 2003, the authors generated clustered logistic regression models, examining associations between provider-based CAM use and receipt of screening tests for Chlamydia trachomatis, breast cancer, and cervical cancer: (1) contrasting women who used CAM providers only (alternative use) and women who used both conventional and CAM providers (complementary use) with women who used conventional care only and (2) testing associations between screening and use of four specific CAM provider types-naturopathic physicians, chiropractors, massage therapists, and acupuncturists. RESULTS: Both alternative and complementary use was associated with reduced Chlamydia screening. Cancer screening increased with complementary use but decreased with alternative use of CAM. Use of naturopathy was associated with decreased mammography, whereas all four CAM therapies were positively associated with Papanicolaou testing. CONCLUSIONS: When used in conjunction with conventional care, use of provider-based CAM may signal high interest in various types of health-promoting behavior, including cancer screening. Negative associations between CAM and Chlamydia screening and between naturopathy and mammography require additional study. Interventions with CAM providers and their patients, aimed at improving rates of conventionally recommended screening, might encourage greater focus on preventive care, an important task when CAM providers serve as women's only contact with the healthcare system.