<p>Opportunity for multiple mating should affect the fitness cost of sexual cannibalism for males. We used newly developed microsatellite loci to study multiple paternity in a wild population of the sexually cannibalistic praying mantid, <i>Tenodera sinensis</i>. We show a high rate of multiple paternity, with offspring from 84% of oothecae (egg cases) sired by multiple males. We also show a low level of paternal skew, suggesting sperm mixing within spermatheca and opportunity for sperm competition. Together, these results suggest significant fitness benefits of multiple mating for males and thus significant sexual conflict over sexual cannibalism, a result consistent with previous behavioral studies. We also use these data on allelic variation for a first look at the genetic structure of mantid populations. Our results show significantly greater homozygosity than expected due to both inbreeding and differentiation among local populations, suggesting restricted dispersal among local populations.</p>