Exposure to electromagnetic fields (EMFs) from use of electric blankets and other in-home electrical appliances has been hypothesized to increase breast cancer risk. To test the hypothesis, the authors analyzed data from a case-control study of female breast cancer conducted in Connecticut in 1994-1997. A total of 608 incident breast cancer patients and 609 age frequency-matched controls, 31-85 years old, were interviewed by trained study interviewers using a standardized, structured questionnaire to obtain information on lifetime use of various in-home electrical appliances. A total of 40% of the cases and 43% of the controls reported regular use of electric blankets in their lifetime, which gave an adjusted odds ratio of 0.9 (95% confidence interval (CI): 0.7, 1.1). For those who reported using electric blankets continuously throughout the night, the adjusted odds ratio was 0.9 (95% CI: 0.7, 1.2) when compared with never users. The risk did not vary according to age at first use, duration of use, or menopausal and estrogen receptor status. The authors also did not find an association between use of other major in-home electrical appliances and breast cancer risk. In conclusion, exposure to EMFs from in-home electrical appliance use was not found to increase breast cancer risk in this study.