36, see text The Natricinae are a subfamily of colubroid snakes, sometimes referred to as a family (Natricidae).

Some Old World members of the subfamily are known as keelbacks, because their dorsal scales exhibit strong keeling.

A single species, Tropidonophis mairii, reaches Australia.

Although the highest diversity is in North America, the oldest members are in Asia and Africa, suggesting an Old World origin for the group.

Most species are harmless to humans, but a few (e.g., Thamnophis sirtalis, Thamnophis elegans) are capable of inflicting bites that can result in local, non-life-threatening symptoms, and at least two members of the genus Rhabdophis (R. tigrinus and R. subminiatus) are capable of inflicting life-threatening bites to humans, though they have only enlarged, ungrooved fangs in the back of the mouth.