Abstract: A system and method are for valuation of complex systems. As a result, a detailed and complete assessment of the current and future state of a complex system can take place. The system and method provide a fully objective, transparent, and accurate way for valuing a complex system because the valuation result is calculated as the integration of detailed valuations of the complex system's constituents. The system and method further provide a complete and consistent treatment of the uncertainties associated with future expectations. The system and method include a structuring method that divides the complex system into representative constituents; a data management system that can collect and store data and results; an expert system that can analyze the data, and; an integration system that can aggregate all appearing quantities including their uncertainties. As optional part it also includes an optimization system and method.