The aim of this paper is to analyze harmful effects of oil spills the marine environment and the ways of marine environment protection from oil spills from ships. The paper emphasizes the importance of sustainable development of maritime transport, especially environmental sustainability, in order to preserve marine environment for future generations and to operate in environmentally, economically and socially acceptable way. The paper consists of seven chapters. After the introductory chapter, the second chapter defines marine environment, emphasizes its importance for the life on the Earth, and emphasizes the problems that arise as the result of increasing human activities at sea. The third chapter analyzes the pollution of marine environment by oils from ships, and provides an overview of the largest maritime accidents in history. The fourth chapter analyzes the processes with oils in marine environment. The fifth chapter deals with marine environment protection from oil pollution from ships and gives an overview of the most important legal instruments globally, regionally (in the Mediterranean) and in the Republic of Croatia. The sixth chapter provides an overview of the basic principles of sustainable shipping. The seventh chapter is the conclusion of the paper.