Immigration constitutes an all time and multi-dimensional social phenomenon. There are quite a few people that in every time period seek a new place of residence and employment, in order to be able to survive or get a better life. The causes which lead to immigration are various and the immigration itself affects not only the immigrants but also the countries of departure and arrival. The immigration phenomenon has occupied and continues to occupy the majority of countries, among which is Greece which has been one of the new host countries for immigrants. The moving of the population presents when the social and economic environment in which an individual lives and moves, does not provide him with the capability to fulfill his pursuits and satisfy his ambitions. The most frequent reason of immigration nowadays is the economic factor and the objective of the individual that immigrates is finding work. In the present project we will study unemployment and employment in the host countries and more specifically in Greece. In Greece during the last years there appears to be an intense influx of immigrants converting it from a departure country to a host country for immigrants. What happens with the working conditions and insurance, how does immigration affect the unemployment of the permanent population, in what kind of jobs are immigrants occupied and do age and sex play a role in finding work? These are some of the questions we are called to answer through this project. The project not only will deal with how immigration affects the working market but also the economy in general (Cholezas and Tsakloglou, 2008). The research part of the project is based on the Greek and European Statistics Service. The statistical data are presented in the form of charts and diagrams. The data actually concern the legal immigrants in the area of Greece and countries of the E.U. (Vgenopoulos, 1988).