The aim of this review is to evaluate the factors related to the doctor and the patient that could make following the guidelines difficult. It also underlines the importance of the adherence to guidelines themselves in order to ameliorate both the control of healthcare and the patients' quality of life. Following guidelines not only depend on factors related to guidelines themselves, to social-cultural context or to the strategies used to spread them: different studies have underlined that the characteristics linked to the doctor's and patient's subjectivity are crucial. Guidelines are recommendations regarding clinical behaviour, and their implementation is a complex process that is influenced by different factors, related both to the characteristics of guidelines themselves and to the social, organizational, economic and political context or to implementation strategies. During the last few years, different studies and theories have tried to explain the reason why doctors and patients do not follow the guidelines. Following the guidelines most of all depends on the characteristics linked to the doctor's and patient's subjectivity, which can be a real obstacle. Knowledge, attitude, skills, experiences, believes and values play a fundamental role both in physician and patient. By addressing these issues to physician's and patient's adherence, more exhaustive approaches to guidelines development and spread can be applied in order to improve care and outcomes.