Morphological correlates of male mating success were assessed in natural populations of three Drosophila species. Mating males in D. simulans were larger than single males but were characterized by reduced developmental stability as indicated by fluctuating asymmetry. Mating male D. pseudoobscura were no larger than single males but exhibited significantly greater developmental stability. In D. mojavensis, however, mating males were larger and they showed a similar level of fluctuating asymmetry to that observed in single males. The differences observed between species are discussed in the context of their mating systems and reproductive ecology.