The number of immigrants entering the European Union countries the last years has been increased. Greece is one of the EU countries that accepts a lot of the immigrants. As a consequence, their pressure to the Greek national health service system has also increased and there is a need to investigate this pressure in detail. The main goal of the present research is to analyze healthcare data concerning immigrants in the region of Eastern Macedonia and Thrace. The data were collected between years 2005 and 2011 from five different hospitals belonging to the Greek national health system, covering the whole Eastern Macedonia and Thrace region. Four characteristics were analyzed, namely the duration of hospitalization, the clinic, the cost of hospitalization and the nationality, using statistical data mining methods. The results show that most of the immigrants were from Albania followed by the ones from Bulgaria, Georgia, Russia, Germany and others. The total cost of the health services applied to immigrants was generally lower than the one for Greek nationality patients and the days of hospitalization have a high impact on cost. Immigrants from specific countries are related to different clinics. Key Words: Immigrants, Cost, Data Mining, Healthcare, Multiple Correspondence Analyses, Linear Mixed Effects Models.