Decades of research on sexual selection have demonstrated that ‘conventional’ Darwinian sex roles are common in species with anisogamous gametes, with those species often exhibiting male-biased sexual selection. Yet, mating system characteristics such as long-term sperm storage and polyandry have the capacity to disrupt this pattern. Here, these ideas were explored by quantifying sexual selection metrics for the western diamond-backed rattlesnake (
Crotalus atrox
). A significant standardized sexual selection gradient was not found for males (
β
SS
= 0.588,
p
= 0.199) or females (
β
SS
= 0.151,
p
= 0.664), and opportunities for sexual selection (
I
s
) and selection (
I
) did not differ between males (
I
s
= 0.069,
I
= 0.360) and females (
I
s
= 0.284,
I
= 0.424; both
p
> 0.05). Furthermore, the sexes did not differ in the maximum intensity of precopulatory sexual selection (males:
s′
max
= 0.155, females:
s′
max
= 0.080;
p
> 0.05). Finally, there was no evidence that male snout–vent length, a trait associated with mating advantage, is a target of sexual selection (
p
> 0.05). These results suggest a lack of male-biased sexual selection in this population. Mating system characteristics that could erode male-biased sexual selection, despite the presence of conventional Darwinian sex roles, are discussed.
No evidence of male-biased sexual selection in a snake with conventional Darwinian sex roles
