According to sexual cannibalism theory, male complicity in terminal mating can be adaptive when the male’s future reproductive value is low relative to the benefits of self sacrifice. Characteristics that lower the male’s chances of successfully mating with a second female may make such male sacrifice behavior more likely to evolve. Spiders and insects that exhibit male sacrifice often also have male genitalia that become broken or disfigured during copulation. Male genital mutilation has great potential for lowering the future reproductive value of the male, which could easily tilt the equation in favor of various forms of male sacrifice. Here I test the hypothesis that the evolution of male sacrifice behavior (either complicity in cannibalism or spontaneous death associated with copulation) is concentrated in taxa where male genital mutilation is a typical consequence of copulation. The concentrated changes test, a phylogeny-based statistic, is used to investigate character correlations. This investigation focuses on araneoid spiders because several independent origins of sacrifice behavior are know for this group and the phylogenic structure of the lineage is relatively well tested. I report that male genital mutilation is significantly correlated with sacrifice behavior and argue that this finding is consistent with sexual cannibalism theory. Male genital mutilation and male sacrifice behavior both tend to evolve under conditions of intense male-male competition. This pattern may also hold for some insect systems. No previous study has identified a morphological characteristic that may be correlated with the repeated evolution of male sacrifice behavior.