This thesis is about the necessity of strong cooperation between Greece and Turkey to solve migration crisis in the European Union. The wave of illegal immigrants to Greece started in 2010. Migrants come to Greece trough the territory of Turkey. Greece and Turkey in 2001 have signed a readmission agreement. On 16 December 2013 Turkey and European Union signed another special readmission agreement. However as a breakthrough we may see an extraordinary summit between European Union and Turkey in 2016. In a few weeks (April 2016) from the summit we may say that it has brought positive changes. However, to solve migration crisis in Europe there must be full cooperation between Greece and Turkey based on trust and respect.