The terrorist attacks in Madrid on March 11, 2004 were one of the most traumatic events in recent Spanish domestic history, and have had a profound influence in internal policy as well as determining the strategy of its foreign and security policy. In many sectors it has created a climate in which there are serious negative repercussions in the acceptance and integration of immigrants from Morocco, bearing in mind that most of the people detained and put on trial are from that country but were residing in Spain. However, if the March 11 terrorist attacks are an important factor militating against Moroccan integration in Spain, the truth is that for many years they have had greater difficulties in integrating into the host community than other immigrant groups. This paper argues that Spanish-Moroccan political relations constitute further factors that create special difficulties for Moroccan immigrants in their integration into Spanish society. In order to demonstrate this hypothesis, the paper first describes in section one the specific Spanish migration context, firstly from the demographic point of view, analysing the rapid change of Spain from an emigrant country to an immigrant country and the increase in foreign population over recent years and, secondly from cultural point of view when it discusses the already existing diversities among the different Spanish regions and, finally, from a legal point of view the paper studies the changeable and unstable Spanish law on migration. The main goal of this introductory section is to show the general problems of integration applicable to all immigrant groups living in Spain, including Moroccans. Secondly, in sections two and three, the paper attempts to examine the unequal treatment against Moroccan immigrants and argues that this situation is not only due to Spanish attitudes toward immigrants in general and the social, racial and religious characteristic of Moroccan immigrants but also because there are other political reasons related to the relations between the Spanish and Moroccan Governments that affect the situation of Moroccans in Spain because of their nationality. In order to show this unequal treatment of Moroccan immigrants in comparison with other immigrant groups, section two describes the main examples of clear discrimination: specific racist and xenophobic attacks against Moroccans in Spain; employment discrimination against Moroccans; and the institutional declarations that negatively affect Moroccans. The third section attempts to demonstrate how old and recent political crisis and controversies in the fields of fishing, agricultural, territorial disputes, and illegal immigration controls between both countries constitute factors which have made the integration of Moroccan labourers in Spain more difficult. The fourth section shows how the political crises and conflicts between Spain and Morocco have worsened the Spanish population's perception of Morocco and have influenced the treatment Moroccan immigrants receive in Spain. Finally, the last section contains several conclusions as a warning to the Spanish Government to improve its relations with Moroccan Authorities not only to obtain institutional and political results but also to bring about positive consequences for Moroccans living in Spain.