Isertia is a genus of flowering plants in the family Rubiaceae.

It contains 15 species of shrubs or small trees that are indigenous to the neotropics.

[3] The generic name honors the German botanist and explorer Paul Erdmann Isert.

In section Isertia, the fruit is a pyrene and the ovary usually has five or six locules.

[5] Molecular phylogenetic studies have shown that Isertia is most closely related to Kerianthera, a monospecific genus from Amazonian Brazil.