Orthogastropoda was a major taxonomic grouping of snails and slugs, an extremely large subclass within the huge class Gastropoda according to the older taxonomy of the Gastropoda (Ponder & Lindberg, 1997).

This taxon is no longer used according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005.

Ponder and Lindberg (1997) in the book The Southern Synthesis, showed the Orthogastropoda as one of two subclasses of the Gastropoda, the other subclass being a very much smaller group called the Eogastropoda, which contained only 5 families of true limpets.

The Orthogastropoda appeared to form a clade which was supported by unambiguous synapomorphies.

Some of the characteristics were: The following is based on the somewhat out-dated taxonomy of the Gastropoda (Ponder & Lindberg, 1997).