Marine concrete structures such as harbors, ports and bridges are exposed simultaneously to the action of physical and chemical deterioration processes. Deterioration of marine concrete structures and its rehabilitation are challenges of the world of today. Recently, the increasing usage of carbon fiber reinforced polymer (CFRP) composite appears to be a solution for rehabilitation and strengthening of the concrete structures because of its physical and mechanical properties, such as high strength-to-weight ratio, high corrosion /environmental degradation resistance, and easy to handle during construction. In general, rehabilitation of concrete structures is usually done by two types of materials, it is either using cementitious or advanced composite materials. The aim of this paper is to address the issues and challenges of concrete structures in marine environments and strengthening these structures. In the initial part of this paper, an overview of the problems associated with marine environment on concrete structure will be discussed. © (2014) Trans Tech Publications, Switzerland.