This study investigated the relation among perceived social support, uncertainty, and quality of life in older survivors with breast cancer. Proposed hypotheses predicted a significant positive correlation between perceived social support and quality of life, and a significant negative correlation between uncertainty and quality of life. It also was hypothesized that perceived social support and uncertainty, considered together, could explain more quality-of-life variance than either variable considered independently. A sample of 103 breast cancer survivors older than 50 years completed the Social Support Questionnaire, the Mishel Uncertainty in Illness Scale – Community Form, and the Ferrans and Powers Quality-of-Life Index – Cancer Version. Data were analyzed using Pearson product-moment correlation, t tests, analysis of variance, and stepwise multiple regression. All the hypotheses were supported. Additional findings showed significant positive correlations between age and uncertainty, and between support network size and social support. Significant negative correlations were found between age and perceived social support, and between age and size of support network. Uncertainty increased in the presence of other diseases, which were associated with poorer quality of life. The study results underscore the importance of social support in reducing illness uncertainty and improving the quality of life for older survivors of breast cancer.