BACKGROUND Women in low- and middle-income countries account for 51% of breast cancer cases globally. These patients often delay seeking care and, therefore, present with advanced disease, partly because of fear of catastrophic health care expenses. Although there have been efforts to make health care affordable in low- and middle-income countries, the financial burden of out-of-pocket (OOP) expenses for nonmedical costs, such as transportation and lost wages, often is overlooked. METHODS An institutional review board exemption was granted from Boston Children's Hospital and Partners in Health/Zanmi Lasante for this cross-sectional study. In total, 61 patients receiving breast cancer care free of charge at Hôpital Universitaire de Mirebalais (HUM) in Haiti were selected via convenience sampling. They were interviewed between March and May 2014 to quantify the expenses they incurred during the course of diagnosis and treatment. These expenses included medical costs at outside facilities, as well as nonmedical costs (eg, transportation, meals, etc). RESULTS The median, nonmedical OOP expenses incurred by breast cancer patients at HUM were $233 (95% confidence interval [95% CI] $170-304) for diagnostic visits, $259 (95% CI $200-533) for chemotherapy visits, and $38 (95% CI $23-140) for surgery visits. The median total OOP expense (including medical costs) was $717 (95% CI $619-1,171). To pay for these expenses, 52% of participants stated that they went into debt; however, the amount of debt was not quantified. The median income of these patients was $1,333 (95% CI $778-2,640), and the median sum of OOP expenses and lost wages was $2,996 (95% CI $1,676-5,179). CONCLUSION Despite receiving free care: at HUM, more than two-thirds of participants met conservative criteria for catastrophic medical expenses (defined as spending more than 40% of their potential household income on OOP payments). Further studies are needed to understand the magnitude of OOP health care expenses for the poor worldwide, how to aid them during their treatment program, and its impact on their health outcomes.