Satellite DNAs of the Drosophila willistoni group have been analyzed by Hae III endonuclease digestion. Differences were observed between the 2 species D. willistoni and D. paulistorum and also between semispecies of D. paulistorum and, to a lesser extent, between subspecies of D. willistoni. Differences did not appear to be consistently greater between strains producing sterile hybrid males than between those producing fertile hybrids. © 1980 Birkhäuser Verlag.