The transport sector is one of the strongest economic and regionally balanced development factors and has a significant impact on national networking as well as it enables access to the world market. Maritime traffic as a part of the national transport system gets even more important if one considers that one of the main features of the contemporary market competition is globalization whose foundation is the cheap and massive transportation of raw materials and goods around the world. Namely, at the time of the open world market where there is an increasing number of (variety) goods, there is no surprise that there is an increasing need for their (international) exchange, especially via seas and oceans. Approximately 80% of the world's trade by volume and 70% of the value goes by sea. Except as transport media, the sea and the oceans are an important factor in the European economy and have great potential for innovation and growth. It is precisely the maritime sector that is emphasized in the EU 2020 strategy for smart, sustainable and inclusive growth. Today, the "blue economy" offers approximately 5.4 million jobs and generates a gross value added of 500 billion euros annually. This doctoral dissertation deals with the study of the economic effects of maritime transport and transport in the function of economic development. In other words, the question is to what extent are the economic effects of traffic recognized as potential accelerators of the economic development of the Republic of Croatia, since it is recognized as a maritime country in the international environment, where some of the most important branches of the economy are related to the sea or maritime affairs. The purpose of the research is to investigate the impact of the economic effects of maritime transport and transport on economic development with a special focus on the economic development of Split. The city of Split is naturally imposed as the narrow focus of this doctoral dissertation, given that various forms of maritime traffic and transport are represented in Split. As such the city of Split represents an ideal platform for scientific and practical discussion on the importance of a particular form of maritime traffic and transport for the economy of Split. Maritime traffic is particularly multiplied to accelerating tourism in Split. The aims of theoretical and empirical research were multifaceted, and they are manifested in the systematization of theoretical and empirical insights on the impact of maritime traffic and transport on a balanced and sustainable development of the national economy; in analyzing the potential of maritime activities in the Republic of Croatia with special reference to the city of Split and ultimately suggesting the guidelines for improving Split's maritime operations and marine operations with the support of the Ministry, port associations, port administrations and major stakeholders in their business. These guidelines can serve all port administrations and other maritime business systems in the development of their own, specific organization and management model that best corresponds to the business environment. The dissertation is divided into a theoretical and empirical part. The theoretical part of the dissertation focuses on the theoretical discussion of maritime affairs as economic activity and the maritime economy, which in recent times increasingly attracts the attention of scientists and decision-makers in view of the multiple impacts that maritime affairs have on economic and social development. The empirical part of the dissertation deals with the scientific validation of the hypothesis set based on the conducted research. As a method of collecting data, a structured questionnaire was used to collect the views of the concessionaires who carry out economic activity in the port area of Split. As a corrective method, there was an interview with selected experts from the activities involved in maritime traffic and transport of the Split port, but the maritime activities are not their primary economic component. The data collected by the conducted survey were analyzed by quantitative methods, the statistical program IBM SPSS Statistics. Statistical analysis was performed using descriptive statistics (percentages, mean values, dispersion measures), nonparametric statistical tests: Spearman correlation analysis, Friedman test, test markers, Hi-squared test. This PhD dissertation gave its scientific and applicative contribution in further scientific and practical research and discussion on the economic effects of maritime traffic and transport on economic development, which can serve as an incentive and motivation for further research on this current topic. It can equally serve to the public policy makers in the design of strategies and measures that would include the effects of maritime traffic and transport in development strategies aiming to increase national competitiveness at a time marked by intense changes and trends brought about by globalization.