The present study was conducted to provide the basis for improvement of clinical nutrition services through development of job standards of clinical dietitian for the clinical nutrition therapy to cancer patients in hospitals. Developing A Curriculum (DACUM) method was used for job analysis and development of job standards for clinical dietitians for cancer care. Based on DACUM analysis, information about duties, tasks, and task elements of clinical dietitians for cancer care was collected. Developed job standards were applied to clinical nutrition care for cancer patients in hospitals for evaluation. Based on DACUM analysis, consultations from professionals, and field application tests, the final job standards were composed of four duties, 18 tasks, and 56 task elements. The duties consisted of nutritional assessment, nutrition diagnosis, nutrition intervention, and nutrition monitoring.evaluation. For cancer nutrition care, 109 work activities were developed. They were composed of 75 basic and 34 recommended work activities. The application of developed job standards for clinical dietitians for cancer care at 10 hospitals showed a performance rate of 72.3%. In conclusion, job standards for clinical dietitians for cancer care developed in this study might be effectively used as guidelines for providing clinical nutrition services for cancer patients in hospitals.