Objectives: Health is a central and important concept in nursing and nursing education, and has been theorised about in both positive and negative terms. The purpose of this study was to explore Swedish nursing students' perceptions of the concept of health. Design: A phenomenographic research approach was used to understand how nursing students perceive the concept of health. Setting: The study group comprised students (n = 233) attending the nursing programme in the first, third and sixth semester, at one university in northern Sweden. Method: Data were collected during the 2012-2013 school year by asking the nursing students to complete the sentence, 'I perceive that health is …' Results: Results indicated that health means a feeling of well-being in both body and mind and that a person is responsible for promoting his or her own health. Promoting good health involved finding a balance between, diet, activity, work and rest. Furthermore, relationships with family and friends were important for experiences of good health. Study participants also commented that a person could feel healthy despite illness. Discussion: Nursing students' perception of the concept of health was multifaceted and based on a holistic and positive attitude. However, the boundary between health and illness was characterised as being unclear, and none of the students' included nursing theory in their descriptions of the concept of health. Conclusion: These findings show that it is important to integrate students' experiences and perceptions into nursing education and theory, to develop a deeper understanding of the concept of health to enhance nursing education.