Human relations with biodiversity are complex, controversial and fluctuating. From the realization of the need to protect and preserve the living being, to the formulation and implementation of devices designed to satisfy them, for the property of present-day societies as well as future generations, it is the future of all mankind, which is played inexorably and irreversibly. The transcendental values of nature and the functions of ecosystems are today more and more frequently and systematically emphasized. However, the road to effective conservation and sustainable use of biodiversity remains long and fraught with multiple obstacles, some of which pose major challenges for the ‘reasonable’ man in his quest for better living in a healthy and protected environment. Between ontology and axiology, the ethics of biodiversity prove to be a major challenge for humanity. The law alone can not satisfy it, even if it tries to bring pertinent but perfectible replies. The expected results will have to be assessed both in terms of the dynamics of biodiversity and societal changes, and of the satisfaction of the objectives lucidly fixed and assumed in this field. The paradox lies in the fact that man, on whom the future, and thus the perpetuation or disappearance of biodiversity, depend, because he is its greatest predator and destroyer, remains both the most dependent and the most vulnerable from it.