This study attempts to analyze long-run and short-run relationships between domestic and international grain prices; and judge whether there was a significant causality relationship between them. The results indicate that international grain prices have a positive effect on the domestic prices, and international prices increased the domestic prices during and after the 2007-2008 grain price-crisis. For causality, in short-run term, for rice in Nicaragua and Tunisia, for wheat in Georgia, Pakistan and Armenia, international prices significantly affected domestic prices; in the long-run, for rice in Dominican, Nicaragua and Tunisia, for wheat in Armenia, Georgia, Mauritania and Pakistan, and for maize in Chad, Guatemala and Nicaragua, domestic prices may be influenced by international prices.