This paper introduces the background and fundamental aspects of chaos and complexity together with the differences and the links between chaos and complexity, and the distinction between complicatedness and complexity with reference to issues in business administration. There is a need to be cautious when using chaos and complexity models in business administration, not to provide a superficial characterization of reality within a confused narrative. Besides, the application of these theories and models is accompanied with several rationales and logic, such as dialogic reasoning, circumscription, the logic of belief, paraconsistent logic, adductive and default reasoning. All these logic and rationale are applied in business administration and specifically in financial statements analysis, management discussion and analysis and notes to financial statements. There seems to be a need and an opportunity for the use of chaos and complexity in business administration; new logic and models are ready to be applied with solid foundations, but they require new forms of thinking. Key words: Business administration, management, chaos, complexity, financial statements.