The Memorandum of Understanding (MOU) is the document of intent signed between the Port States Control(PSC) to undertake a uniform as agreed. Though the MOU is not a legally binding, in case where the agreed items are violated without a just cause, the denunciation will follow. International Maritime Organization (IMO) and regional MOUs have been making amendments and reinforcing the relevant requirements, so that port State Authorities can effectively eradicate the substandard vessels. However, the various problems have arisen due to the existence of different requirements of each MOU, the lack of information exchange between each MOU, the lack of uniform PSC implementation within the same MOU and the lack of adequate system due to the short history of MOUs. In this paper, the MOU records for three years (1999∼2001) were analyzed according to each MOU, type of ship, deficiency code, classification society, the number of inspected ships and the number of detained ships to assess the problems (Statistics during 2002 will be published after August 2003). The purpose of this study is to help better understand the PSC activities within each MOU and to establish effective countermeasures by grasping the problems that exist in the PSC at present.