The purpose of our experiment was to test the effect of probiotics on the immune system of flies. To do so, we first divided our wildtype Drosophila melanogaster flies into two groups. One group consisted of flies fed on standard (fly) food, and the other group consisted of flies fed on a mixture of standard (fly) food and Actimel. We then tested the strength of their immune system by amputating one of the flies’ front leg and counted the number of flies surviving after three days. With these results we were able to conclude that the Actimel seems to strengthen the flies’ immune system. However we would like to perform more trials and further investigations to confirm these results (and consequently implications).