Immunity and reproduction are two important processes that contribute to organismal fitness. Sexual activity has been previously shown to determine the degree to which organisms are able to survive infection. While many studies have demonstrated a trade-off between immune function and reproduction, other studies have found a synergistic relationship between the two fitness determinants. It is also generally hypothesised that the sexes may differ in immunity due to sex-specific costs incurred during reproduction, with males sacrificing immune function to increase their reproductive success. In this study, we tested the effect of immune function on the survival of mated and virgin replicates of a large outbred baseline D. melanogaster population that was infected with four different bacterial infections. We found enhanced survival of infection in mated flies relative to virgin flies in response to all four bacterial infections across all replicates. We also found no evidence for sexual dimorphism in this response, as there was no difference between males and females in their ability to survive the imposed bacterial infections. Synergistic interaction between reproduction and immune function may exist if it improves overall individual fitness in populations under selection, and are not necessarily limited by each other due to trade-off over finite resources.