Porthidium dunni is a species of pit viper in the family Viperidae.

[4] The specific name, dunni, is in honor of American herpetologist Emmett Reid Dunn[5] "in appreciation of his work on American snake fauna".

[3] P. dunni is found in southern Mexico in the Pacific lowlands of Oaxaca and western Chiapas.

[7] The type locality given is "the immediate vicinity of the village of Tehuantepec" [Oaxaca, Mexico].

[1] Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category.