Bothrops pirajai, commonly known as Piraja's lancehead,[3] is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae.

[4] The specific name, pirajai, is in honor of Brazilian parasitologist Pirajá da Silva, who in 1923 was director of the Bahia branch of the Instituto Butantan.

[2] The species B. pirajai is classified as endangered on the IUCN Red List for the following criteria: A1c (v2.3, 1994).

[1] This means that it is facing a high risk of extinction in the wild in the medium-term future due to population reduction in the form of an observed, estimated, inferred or suspected reduction of at least 20% over the last 10 years or three generations, whichever is the longer, based on a decline in area of occupancy, extent of occurrence and/or quality of habitat.

The rainforest inhabited by this species is unfortunately decreasing in area and quality, while becoming increasingly fragmented through deforestation.