Background: Financial distress due to the cost of cancer treatments is prevalent among cancer patients. Identifying the level of financial distress and its affecting factors has an important role in providing supportive services. Accordingly, the aims of this study were to determine these parameters among Iranian cancer patients. Materials and Methods: This descriptive-correlational study was undertaken among 262 cancer patients admitted to both private and public hospitals in East Azerbaijan province, Iran. The financial distress/financial well being scale was used to determine financial distress. The data were analyzed using SPSS software using descriptive and inferential statistics (multiple linear regression). Results: Among the 262 cancer patients, 57.3% were male and their mean age was 47.0 years. The mean score for financial distress was 4.12 (2.01). The final regression model demonstrated that the independent variables (predictors) of income less than living expenses, income equal to living expenses, having an employed spouse in governmental job and living with parents, with regression coefficients of -1.029, -0.515, 0.198, and 0.096, respectively, were predictors of financial distress among cancer patients. These variables accounted for 50% of changes in variance of financial distress. Conclusions: Iranian cancer patients have moderate to high levels of financial distress. Considering policies for managing direct and indirect costs of cancer treatments must be followed.