Metlapilcoatlus mexicanus is a pit viper species[4] endemic to Mexico and Central America.

Adults grow to an average of 50–70 cm (about 20–28 inches) in total length.

[3] Found in the Atlantic drainage from Mexico (in the Mexican states of Tabasco and Chiapas) south to the Canal Zone in Panama, both slopes of Costa Rica and Panama.

[3] The type locality given is "Coban, capitale de la province de la Véra-Paz, (République de Guatemala, Amérique centrale)" (Cobán, Alta Verapaz, Guatemala).

[2] Regarded as a full species, Metlapilcoatlus mexicanus, by Campbell and Lamar (2004).