A small, unusual group of advanced snakes, often called mole vipers or stilleto snakes. Recently, molecular evidence has shown that this family includes many genera formerly classed in other families, on the basis of fang type. This odd family of snakes seems to include fangless (aglyphous ), rear-fanged (opisthoglyphous ), fixed-fanged (proteroglyphous ), and viper-like (solenoglyphous ) species. Molecular and physiological data linking this family to others is ambiguous and often contradictory, which means the taxonomy of this family is highly contentious.

The most well-known (and most lethal) of this family is Atractaspis itself, a small African snake with fangs that, rather than swinging forward like those of a viper, swing outward to the sides, allowing the snake to strike with its mouth closed by swinging its head. This odd behavior has resulted in the envenomation of otherwise cautious herpetologists, including Mark O'Shea , whose accidental bite was caught on film while taping for his TV show, as was his subsequent rush to the nearest hospital. He survived, but others have not been so fortunate in the past.

In summation, members of this family present a fascinating conundrum, but one best handled with extreme caution.