This article analyses the issue of miscegenation in Portugal, which is directly associated with the context of its colonial empire, from late nineteenth to mid-twentieth centuries. The analysis considers sources from both literary and scientific fields. Subsequently, aspects such as interracial marriage, degeneration and segregation as well as the changes brought about by the end of World War II and the social revolutions of the 1960s are considered. The 1980s brought several changes in the attitude towards Portuguese identity and nationality, which had meanwhile cut loose from its colonial context. Crossbreeding was never actually praised in the Portuguese colonial context, and despite still having strong repercussions in the present day, lusotropicalism was based on a fallacious rhetoric of politically motivated propaganda.