Abstract: The current research aimed at investigating mediating marketing knowledge in the effect of cultural intelligence on consumers' decision-making style" by applying on Customers of fast-food restaurants in Mansoura" and the study used the descriptive analytical method and relied on questionnaire in collecting the data. The number of the study sample was (489) individuals. The results of the study found that there is a positive effect of the mediating role of marketing knowledge in effect of cultural intelligence on customer's decision-making style. The results showed that there was an increasing in interpretation of the variables included in model for the changes that occur in a variable and mediating role of marketing knowledge in effect of cultural intelligence on the decision-making style of customer leads to an increasing in the effect of the dimensions of the variables included in the study. The study recommended that for increasing the level of marketing knowledge for consumers, there is a need to provide all information that leads to increasing their knowledge of the products before purchasing them, and the needs of producers to put all the necessary information on the commodity clearly and prominently must be pay attention to.