Background In Spain, there has been great effort by lawmakers to put Advance Directives into practice since 2002. At the same time, the field of bioethics has been on the rise, a discipline that has spurred debate on the right of patients to exercise their autonomy. Despite all this, the implementation of ADs can be said to have failed in Spain, because its prevalence is very low, there is a great lack of knowledge about them and they have very little (...) impact on clinical decisions. The purpose of this article is to analyze and discuss the main reasons for the failure of ADs in Spain. Main body The main reasons why ADs have no impact on clinical practice in Spain have been fundamentally four: the training of health professionals about the end of life and AD is lacking; there has been no public process to increase awareness about AD, and therefore people know little about them; the bureaucratic procedure to document and implement ADs is excessively complex and cumbersome, creating a significant barrier to their application; in Spain, the remnants of a paternalistic medical culture continue to exist, which causes shared decision-making to be difficult. Conclusion Due to the four reasons mentioned above, AD have not been a useful tool to help honor patients’ autonomous decisions about their future care and, therefore, they have not achieved their objective. However, despite the difficulties and problems identified, it has also been observed that health care professionals and the Spanish public have a very positive view of AD. Having identified the problems which have kept AD from being successful, strategies must be developed to help improve their implementation into the future. (shrink)