According to this FEANTSA report: http://www.feantsa.org/code/en/country.asp?ID=8&Page=22
"Today, Greece is placed among the E.U. countries with very high owner occupancy rates (74%) but this number includes a significant number of households (approximately 1/3) who live in poor housing conditions. Compared to other European Member States, homelessness in Greece has only recently been understood to be a social problem, mostly by NGOs. Homelessness, however, has clearly escalated in the last few years due, to a great extent, to the influx of a large number of immigrants from neighbouring countries (Eastern Europe).
Although the Greek Constitution states that the provision of accommodation to people who are homeless or housed in unsuitable conditions constitutes a special task for the State, there is no statutory obligation of local or central government to provide suitable accommodation and support to such people in need. On the contrary statutory practices aim at shifting housing responsibilities to poor families and NGOs without adequate funding.
Traditionally, accommodation problems in Greece have been handled within families. The family – rather than any form of state provision – constitutes the main safety net against homelessness in Greek society to this day. Nonetheless, familistic, religious, and nationalistic values of both social and state actors serve the concealment of homelessness. Social housing provision is minimal and does not even target homeless people. The growing awareness and concern about homelessness in recent years has however led to the creation of various methods to address homelessness, including a limited number of specialised services.
There is severe lack of reliable official data on housing and homelessness in Greece. Research data suggest that the number of street homeless people and those in transitory shelters in the city of Athens is approximately 11,000 (3,000 Greeks and 8,000 foreigners). "