This article describes the most typical characteristics of complex adaptive systems (CAS) theory and how it works in healthcare organizations and nursing practice. Complexity science belongs to newest systems thinking, which explore complex systems by focusing on the system components, relationships and interconnections rather than on the individual components themselves. The nurse must therefore always keep in mind the larger picture when caring for the individual patient and expect to be disturbed by unexpected possibilities. The incorporation of complexity science concepts into the practice of nursing leadership encourages new ways of thinking about organizations and is a natural model for the ideals and expected results of skilled nursing. CAS theory will take a permanent place in the healthcare organizations activities, improve nursing processes and create a better work environment for nursing and job satisfaction.