It really depends what loans you pick. Last year capital one was matching 'loans' to US based Kiva affiliates and I put quite a bit of loans there. Many of them defaulted.

I'm administering 1000$ donated to Kiva in 2009 and 2010 during the SMD1 & SMD2, basically re-lending all repayments as they become available:


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With each default, the pot shrinks a bit. So far I've lost 240$ of 1000 over about 4-5 years. I continue to relend, but in general I'm very skeptical of Kiva and how they handle defaults.