This study explored the influence of different components of the social networks of women with breast cancer on the quality of life. In this study, 79 women (18-60 years) completed a questionnaire about their quality of life (EORTC QLQ C30) and their social relationships at the beginning of an inpatient rehabilitation program (which occurred an average of 10 months after the diagnosis) and three month after the end of the rehabilitation program. The most frequently mentioned relationships were based on the family network. Compared with family members, significant persons in the non-family network were older and more often female. The family network size as well as the measurement time had a significant influence on the quality of life of women with breast cancer. The majority of women with breast cancer participating in a rehabilitation program have a network of emotionally meaningful persons. The knowledge about the composition of the social network can provide valuable information throughout the entire rehabilitation process.