The continuum of breast cancer care requires multidisciplinary efforts. Patient navigators, who perform outreach, coordination, and education, have been shown to improve some areas of care. However, little research has assessed the impact of navigators on breast cancer treatment in uninsured populations. Our objective is to report on the impact of a patient navigator program on breast cancer quality of care at a public hospital. One hundred consecutive newly diagnosed patients with breast cancer (Stages I to III) were identified (2005 to 2007). Forty-nine patients were treated before the use of navigators and 51 after program implementation. Nine breast cancer quality indicators were used to evaluate quality of care. Overall adherence to the quality indicators improved from 69 to 86 per cent with the use of patient navigators (P < 0.01). Only one individual indicator, use of surveillance mammography, improved significantly (52 to 76%, P < 0.05). All nine indicators reached 75 per cent or greater adherence rates after implementation of the navigator program compared with only four before implementation. Patient navigators appear to improve breast cancer quality of care in a public hospital. In populations in which cultural, linguistic, and financial barriers are prevalent, navigator programs can be effective in narrowing the observed gaps in the quality of cancer care.