This study elucidates the nursing of undernourished patients as experienced by eight registered clinical nurses and five nursing assistants by using content analysis. The participants' narratives describe the inner perspective of caring for undernourished patients, known in Sweden as `the thin ones'. Categories identified were: frustration in nursing, joy in nursing and that undernourishment is taboo. The taboo was narrated as feelings of guilt and shame. Frustration in nursing could be seen as feeling stressed, exposed, lonely, powerless, helpless, and being torn between demands and needs. Joy in nursing was experienced when creating a trusting relationship, promoting pleasure in the meal situation and working with respect for each individual's life-style and context of life. Understanding staff members' views is important when implementing guidelines as well as in the teaching situation in order to identify where staff stand with regard to knowledge and attitudes.