In today’s health care it’s most common to treat an illness with a kind of pharmaceutical preparation. But lack of resources, given information and bad communication and collaboration between the patient and the nursing staff can lead to a patient unwilling to follow the doctor’s prescription. This does not just affect the individual patient’s health but it can also result in consequences for other people and the whole society. The purpose of this study was to analyse studies about the concepts compliance and concordance in order to illustrate why patients with chronic illnesses fail to follow their prescriptions. Our method has been to read and analyse the methods and results of articles out of the perspective similarities and differences of the concepts compliance and concordance. It was hard to keep the concepts separated because of their similar meanings. Our result shows that the method used was interviews with questionnaires which has been analysed on the basis of the qualitative studies’ themes and categories. The quantitative articles’ data were displayed statistically. Our analyse showed that patients often lack knowledge about their medical treatment which affects their attitudes and can lead to bad compliance and concordance. As a nurse it’s therefore important to identify the cause that affects the patient. The nursing staff’s goal ought thus to be to get the patient involved as much as possible in their self-care. If the patient is involved in hers/his treatment, it’s more likely that they feel a responsibility towards themselves and therefore gets a better quality of life.