The management of differences that emerged as a result of globalization in the late 1980’s, as it turned out to be extremely important in the success of global business, has become an important study subject in global businesses. The subject of managing differences has become quite interesting not only for social scientists or managers, but also for ordinary people who encounters different cultures in their daily life. It is very important for the permanence of global companies to understand the differences in global companies and manage these differences effectively and hence to minimize the negative effects raised by the differences. Also, some regulations need to be done by the workers and the business managers to maximize the positive effects of the differences. In this thesis, globalisation, global companies, variation elements in global companies and suggestions for effective management of cultural differences are emphasized.