The aim of this study was to investigate the quality of Swedish-language breast cancer information available on the Internet. The questions explored were the extent and type of breast cancer information available, the coverage and correctness of that information, and whether the websites fulfilled the European Commission quality criteria for health-related websites. Three search engines were used to find websites containing medical information on breast cancer. An oncologist then evaluated the 29 relevant sites. Only seven of these were judged suitable for breast cancer patients. The coverage and correctness of the medical information varied considerably. None of the websites fulfilled the European Commission quality criteria. Therefore, considerable effort will be required before the Internet can serve as a valuable and up-to-date source of information on breast cancer for both professionals and laypersons. Our findings broadly match the results of earlier studies of English-language websites.