Polyandry (female multiple mating) has profound evolutionary and ecological implications. Despite considerable work devoted to understanding why females mate multiply, no convincing empirical evidence explains the adaptive value of polyandry. In this study it is provided a direct test of the controversial idea that bet-hedging functions as a risk-spreading strategy that yields multi-generational fitness benefits to polyandrous females. Unfortunately, testing this hypothesis is far from trivial, and the empirical comparison of the across-generations fitness payoffs of a polyandrous (bet hedger) versus a monandrous (non-bet hedger) strategy has never been accomplished because of numerous experimental constraints presented by most ‘model' species. In this study, authors take advantage of the extraordinary tractability and versatility of a marine broadcast spawning invertebrate to overcome these challenges. Multi-generational (geometric mean) fitness among individual females assigned simultaneously to a polyandrous and monandrous mating strategy has been simulated. These approaches, which separate and account for the effects of sexual selection and pure bet-hedging scenarios, reveal that bet-hedging, in addition to sexual selection, can enhance evolutionary fitness in multiply mated females. In addition to offering a tractable experimental approach for addressing bet-hedging theory, this study provides key insights into the evolutionary ecology of sexual interactions. informacion[at]ebd.csic.es: Garcia-Gonzalez et al (2015) Mating portfolios: bet-hedging, sexual selection and female multiple mating. Proc. R. Soc. Lond. B 282:20141525. http://dx.doi.org/10.1098/rspb.2014.1525