Abstract Objective To reflect on the interrelations between Florence Nightingale's Environmentalist Theory and the Ecosystem Theory and their influences on the reparative process of diseases and on the health/disease/care of human beings. Method A theoretical-philosophical reflection on the interrelations between Florence Nightingale's Environmentalist Theory and the Ecosystem Theory, based on authors who discuss this topic. Results Both theories are similar in relation to the search for self-knowledge, self-organization/autopoiesis and the way to visualize the components of reality in human life and its interactions with the environment. Both involve the totality of the environment's biotic and abiotic organisms, and consider that they interrelate, influence, cooperate and interfere in human life. Conclusion and implications for the practice The interrelations between both theories make it possible to construct, in a holistic way, new knowledge about human beings' thinking, seeing, feeling and acting in the universe and of Nursing care, thus apprehending the totality of the needs, and the integration and dynamic balance of being and living healthy.