e North America, Mexico, Central America, South America, e Asia, Atlantic Islands (Madeira).
Clethraceae is often treated to include only Clethra; studies have shown that Purdiaea Planchet, a neotropical genus of about 12 species (most diverse in Cuba), should be included in Clethraceae rather than Cyrillaceae (J. V. Schneider and C. Bayer 2004). This is consistent with the molecular interpretation of Clethraceae as a sister group to Cyrillaceae and Ericaceae.
Genera 2, species ca. 75 (1 genus, 3 species in the flora).