Sistrurus miliarius, commonly called the pygmy rattlesnake, is a species of venomous snake in the subfamily Crotalinae (pit vipers) of the family Viperidae.

[4] S. miliarius is a small species but bulky when it comes to width,[5] with adults usually growing to 40–60 cm (16–24 in) in total length (including tail).

[6] It is currently theorized that the lack of sexual dimorphism in the species is due to the fact that both males and females experience selective pressures to be of a larger size.

[3] Juveniles' color patterns are similar to the adults, although they may be paler or more vividly marked, and the tips of their tails are yellow.

The specific name, miliarius, is derived from Latin and means millet or millet-like, perhaps referring to the blotched patterns described in the species.

[9] S. miliarius is found in the Southeastern United States from southern and eastern North Carolina, south through peninsular Florida and west to East Texas and Oklahoma.

[2] Sistrurus miliarius reportedly inhabits flatwoods, sandhills, mixed forests, and floodplains, and is also found near lakes and marshes.

[24] Pygmy rattlesnakes may change their foraging behaviors, such as prestrike, strike, and poststrike, to be most suitable for the prey item they are going after.

[26] This snake produces cytotoxic venom that is strongly hemorrhagic and tissue toxic, but devoid of any neurotoxins.