The 2003 survey "Passage à la retraite des immigrés" (The Retirement of Immigrants), carried out on a sample of 6,211 immigrants aged between 45 and 70 years old living in Metropolitan France, reveals details about the private mutual financial support networks of migrants. These flows of money are analysed along multiple dimensions, in particular the composition of the mutual support network, the upward or downward movement of financial aid between generations, whether the aid remains in the country or is sent abroad, as well as whether it is given as a gift or a loan. Money transfers sent by the migrant to their country of origin for their personal use are also recognised. The results reveal a specificity of the behaviour of the migrants' transfers as well as their diversification between countries of origin. The migrants' family mutual support networks are not exclusively intergenerational; significant money transfers also occur between siblings. Transfers between generations occur from child to parent as frequently as they do from parent to child, particularly amongst African immigrants, although parents give children the larger amounts of money. With regard to networks outside the family, although they are much smaller than the family network, they nevertheless provide significant financial aid, mainly in the form of loans. Transfers by migrants represent a significant proportion of total transfers and are mostly for personal use by the sender. Whether these transfers are sent to their country of origin or are carried out in the host country, the needs of the recipient are the main motivation for sending monetary gifts, with the migrants playing a «key» role as provider for the whole family. They also play an important social role, maintaining links with the close relatives who remain in the country of origin.