Background: Performing breast self-examination (BSE) every month, starting at age 20 is an important tool in the early detection of breast cancer. Early detection of breast cancer plays a leading role in reducing mortality rates and improving patients' prognosis. Aim: The purpose of the current study was to determine Jordanian nurses' practice of BSE and knowledge about risk factors of breast cancer. Method and Material: A descriptive study design was used, with a sample of convenience 112 of registered nurses and midwives in Zarqa city, Jordan between January and March 2011. A self- administered questionnaire was used for data collection. Results: mean age of the respondents was 29.5; (SD=8.3) years and ranged from 18 to 55 years. More than half of the studied group married and 47.3% worked for more than 5 years 95.5% had no previous breast health problems and family history of breast cancer was reported by 12.5%. Only 19.4% of the studied sample performed BSE regularly. The practice of BSE was not significantly associated with socio-demographic characteristics. Conclusion: study findings suggested that there were gaps between knowledge and practice of BSE among Jordanian nurses.