Survival rate is one of the most poorly characterized components of the life history of many species of reptiles, especially snakes. Reproductive activity can increase the risk of mortality. In this study, we examined whether sex-specific reproductive costs affect the survival probability of a viviparous rattlesnake, Crotalus triseriatus, in central Mexico from 2015 to 2018. We used a multimodel inference framework to test two hypotheses: (1) female survival probability should decrease during the late-gestation and birthing period, when females are less mobile and try to achieve stable body temperatures by behavioral thermoregulation; and (2) male survival probability should decrease during the mating season, when males are more actively searching for potential mates. Our data did not support these hypotheses. Mean (±1 SE) monthly survival probability of both males and females was 0.96 ± 0.01, and recapture probability was 0.11 ± 0.01. Annual survival rate was 0.72 ± 0.12. Monthly estimated mean adult population size varied from 16 to 71 adult rattlesnakes. Survival probability was positively correlated with body size. The reproductive costs could have been obscured by the fact that females do not reproduce every year and, therefore, the demands of the mating season are not as tightly linked to survivorship as we hypothesized.