Promiscuity can drive the evolution of sexual conflict before and after mating occurs. Post-mating, the male ejaculate can selfishly manipulate female physiology leading to a chemical arms race between the sexes. Theory suggests that drift and sexually antagonistic coevolution can cause allopatric populations to evolve different chemical interactions between the sexes, thereby leading to post mating reproductive barriers and speciation. There is, however, little empirical evidence supporting this form of speciation. We tested this theory by creating an experimental evolutionary model of Drosophila melanogaster populations undergoing different levels of interlocus sexual conflict. We found that sexual conflict can cause reproductive isolation in allopatric populations through the co-evolution of chemical (post mating prezygotic) as well as behavioural (pre-mating) interaction between the sexes. Thus, to our knowledge, we provide the first comprehensive evidence of post mating (as well as pre mating) reproductive barriers due to sexual conflict.