The paper is a short survey on microcredit activities and microfinance institutions (MFI), that in the last few decades obtained outstanding results in the fight to poverty. The extremely positive track record has generated high expectations on two different sides: the first related to the sustainability of this business; the second related to the exportability of this business to advanced economies, in order to fight the increasing social exclusion. We argue that both statements can be easily criticized, since most microcredit activities and MFI are still not sustainable; moreover several elements limit the exportability of this peculiar business model to risch countries.