This qualitative study describes ethical challenges faced by Iranian nurses in the process of pain management in surgical units. To address this issue, semistructured interviews were conducted with 26 nurses working in surgery units in three large university hospitals in Tehran. An analysis of the transcripts revealed three main categories: institutional limitations; nurses' proximity to and involvement with pain and suffering; and nurses' fallibility. Specific themes identified within the categories were: insufficient resources, medical hierarchy; difficulties with believing patients' complaints regarding pain and suffering; and experiencing the consequences of poor judgments. Our findings lead us to conclude that, as nurses are much closer to patients' pain and suffering than other health professionals, being aware of their ethical problems, and being able to reflect on them and discuss and learn from them, will reduce the burden of the ethical challenges faced. The findings will help nurses in other countries to devise suitable ways to reduce the ethical burdens they bear in their daily practice.