This paper analyses the impact of a microfinance institution (MFI) serving small informal enterprises in Antananarivo (Madagascar). The methodology consists of comparing over time the situation of a representative sample of clients' enterprises with a control group, constructed in an almost experimental way through a standard propensity-score matching technique. Overall, the results indicate a positive impact of the project. Taken as a snapshot, the evaluations successively conducted in 2001 and 2004 indicate that the clients' enterprises recorded better average performance than enterprises without funding. With a dynamic perspective however, the results are more nuanced. If the positive effect of the project is clear during growth phases, its effect during economic recessions appears less certain.