Port management system is an important segment in sea valorization and country's naval orientation, wherein the developed maritime countries that recognized this long time ago, pay special attention to development of their ports and port management systems, aiming at economic development of hinterlands and development of traffic and economic activities of regions, and countries overall. Classification of ports by their size and level of significance for the Republic of Croatia, and forming port managements is done in order to create economic, legal and theoretical grounds necessary for successful development of national port management systems of each port within the port management system. State analysis of regional ports, annual work reports and financial reports of regional port indicate that there are more disadvantages than there are advantages to the current methods of regional port management. Current methods of regional port management are diverse, with doubtful performance, mostly uneven without optimum and relevant organization or adequate systematic approach. Such management is mostly due to incomplete Act of Maritime Demesne and Sea Ports, which represents the foundation for port managements, because it does not regulate models and methods of regional port system management. Therefore, it is necessary to research, elaborate and consistently determine all relevant features and factors of sea ports and port management systems in general, especially of regional sea ports in the development function of transport infrastructure, superstructure, town and environment as certain parts of each sea port, and to suggest a model, measures and activities for establishing rational structure and organization of regional sea ports with the aim to enable profitable operation and to emphasize the significant multiplicative factor of this segment of Croatian port management system. In evaluation and reaching quality solutions for rational and successful regional sea port management, it is extremely important to improve the procedure for solution selection, which includes defining basic goals, criteria, measures and evaluation of considered solutions. Regional port management must be in conformity with legal and economic settings and guidelines for development of the port management system in the Republic of Croatia, as well as its integration into maritime and traffic system. Rationalization of regional sea port management is inconceivable without accepting all the relevant criteria for forming regional port management systems, where economic criteria must be of exceptional significance. Through adequate evaluation of relevant criteria for forming regional port management system and by application of method of multicriterial decision-making and modeling in doctoral dissertation titled "Rationalization of Regional Sea Port Management", new models of regional sea port management are introduced.. The given model refers to the model of regional port management through mediation of one port management and five branches, and it takes into consideration all the relevant factors and criteria affecting regional port managements as profitable business centers.