After mastectomy, the provision of an appropriate breast prosthesis can help to improve body image and quality of life and reduce associated emotional distress. Although up to 90% of women use an external breast prosthesis after mastectomy, little is known about their experiences and satisfaction with breast prosthesis use. Focus groups were conducted with women who had been fitted with an external breast prosthesis, breast care nurses, and prosthesis fitters to explore women's experiences of prosthesis use. Qualitative thematic content analysis of focus group transcripts indicated that whereas women's initial reaction to the prosthesis generally was negative, this improved over time. Provision of adequate information and support, characteristics of the fitter and the fitting experience, and relationships with breast care nurses and prosthesis fitters were important to women's acceptance and satisfaction with their prosthesis. The study results highlighted the key role that breast care nurses play and the underestimation of the prosthesis fitter's role. Common themes concerning the impact of prosthesis use included body image, appearance, and feminine identity. These findings have important implications for professionals involved in the delivery of breast prostheses services.