Background: Performance of a health system is of great importance since it is the major means for improving health. Until now, various methods have been proposed for assessing the performance of the health system. The method proposed by World Health Organization is based on three major goals of the health system: health improvement, accountability, and equity in financial contribution. Equity of a household's financial contribution in the health system can be determined through the measurement of catastrophic health expenditures. Therefore, the present study aims to determine the percentage of households with cancer patients that face catastrophic health expenditures.Methods: This descriptive-analytical study was conducted in a cross-sectional manner. The statistical community of this research included all households with cancer patients who referred to the chemotherapy and radiotherapy wards of Namazi Hospital, Shiraz, Iran. The study participants were selected by simple random sampling. We used the expenditure part of World Health Organization's Health Survey Questionnaire to gather data related to the 245 study participants. Data analysis was conducted by SPSS statistical software and the chi-square test.Results: According to the results, 67.9% of households with cancer patients faced catastrophic health expenditures. There was a significant relationship between facing these costs and type of insurance, residence, use of outpatient services, type of treatment and other family members who refrained from using healthcare services.Conclusion: The high percentage of households with cancer patients who face catastrophic health expenditures can direct policy makers to develop support policies for these patients and, at the same time, aim at reducing their treatment expenses. Paying special attention to cancer patients, considering cancer as a specific disease, revising the country’s insurance system, and reconsidering the provided services can be the priorities of the health system.