Social and health data on the immigrant population remain scarce in France, especially concerning those in irregular situation. The Baudelaire outpatient clinic in Saint- Antoine hospital in Paris (PASS, i.e. specific free medicosocial care for the poor, the uninsured or the undocumented patients) treats a majority of immigrants, a lot of them being in an irregular residence status. The objectives of this study were to describe the social and health status of the immigrant consultants, to compare regular and undocumented migrants and to describe their main reasons for migration. A cross-sectional, descriptive, survey among the immigrant consultants has been performed among this outpatient clinic in April and May 2009. In total, 536 patients were included. Their age mean was 45 years, 62% are male, 49% are in an irregular situation and they have been in France for 12 years in average (19 years for the regular immigrants and 5 years for the undocumented). More than 20% had no health insurance. A majority (55%) of patients were suffering from a chronic disease. The more frequent ones were hypertension (20%), type 2 diabetes (11.6%), chronic infectious diseases - HIV, HBV, HCV - (7%). Reasons for immigration were mostly economical (39%), family (19%) and political (17%). Health reasons were at the 4th rank and concerned 9% of the patients. The main chronic diseases observed among this population are similar to those of the general population of consultants in primary health care, except for the chronic infectious diseases, which are more frequent. Immigration for health reasons represents only a small proportion of all immigration reasons. For this population, free clinics like the one investigated here constitute unique, irreplaceable, access points in the French healthcare system.