As professionals, social workers have a special position in relation to considering the needs of children with cancer and their families. Hence, it is important to recognize the experiences and challenges of social workers to improve care of their clients. This study was a qualitative content analysis that aimed to determine a comprehensive understanding of 19 pediatric oncology social workers’ experiences in Iran. Data were collected using semi structured interviews and field observations, analyzed through face content analysis. Concepts extracted from social workers’ experiences consisted of the nature of oncology work, lack of professional competence, low organizational support and professional inferiority that were related to main concept of "exhausting and stressful service". The results indicated that social workers' involvement in stressful and emotionally demanding situations and professional and organizational challenges caused personal exhaustion. In addition to explaining the social workers’ experiences and related factors, the results emphasize the importance of taking care of service providers to prevent them becoming stressed and exhausted. It is also important to protect patients from the consequences of stressed and exhausted care providers so further research is recommended to develop specific intervention.