Background: The primary site of cancer in Turkish women is breast cancer. The incidence of breast cancer is increasing in Turkey. Objective: The aim of the research was to educate women 40 years and older to increase their awareness on early detection and diagnosis, to facilitate the use of the early diagnosis methods, to improve the women's beliefs in relation breast cancer, and to increase the use of Cancer Early Diagnosis and Screening Centers available in the city. Methods: The target population of the research was 5000 women. Forty selected women were educated as peer educators. Twenty-five of them were selected as principal peer educator. Each peer educator was expected to educate 200 women. Peer trainers educated their peer and also arranged for the mammography appointment of the women who decided to have theirs taken. Data were obtained before and after the training by Champion's Health Belief Model Scale, questionnaire forms, and Cancer Early Diagnosis and Screening Centers data for mammography practice. Results: Breast cancer was detected in 8 women. Statistical analyses showed positive changes in women's health beliefs and breast self-examination knowledge. There were 20.4% of women (n = 1040) who did get mammograms, and 8% (n = 8) of women were found to have cancer in all of those screened. Conclusion: Peer education was found to be effective for increasing the knowledge, beliefs, and practice of women related to breast cancer. Implications for Practice: Peers can reinforce learning through ongoing contact. Peer education can be used to improve early diagnosis of breast cancer and breast cancer awareness in asymptomatic women.