In the maritime history, globally numerous casualties have been occurred with irreparable consequences. From the establishment of International Maritime Organization (IMO), efforts have been taken to prevent or reduce marine accidents and casualties. Under the pretext of IMO’s sixty year activities, this article highlights the measures of preventive actions in marine accident, carried by IMO and its related bodies.Statistics show that despite growth of shipping activities, measures which have been taken by IMO have reduced marine accident and casualties. IMO was born in conference held in Geneva, in 1948, under the auspices of the United Nations.March 17th will mark the 50th anniversary of that Convention entering into force in 1958.June 2008 will see the 100th meeting of the IMO Council, the executive body of IMO, which is responsible, under the Assembly, for supervising the work of the Organization in between successive sessions of the latter. The theme for World Maritime Day 2008 is "IMO: 60 years in the service of shipping". So accident prevention could be considered as a result of IMO’s work package, although it is not possible to prevent all accidents and casualties, but the important thing is the output of IMO’s service or products which are very effective in marine accident.The article will introduce the related conventions, resolutions, circulars and guidelines for reduction of marine accidents and casualties.