A qualitative study of reflection high-energy electron diffraction (RHEED) patterns shows two distinct surface morphologies for ZnSe epilayers grown on GaAs(1 1 1)B surfaces. These patterns also reveal a reversible transition between these surface structures if growth conditions are modified. Creation of ZnSe mounds on a rough-surface background has been observed for substrate temperatures higher than 400 degreesC and for Se/Zn atomic flux ratios less than 1.00 +/- 0.05. A "wavy" surface structure, with no mounds, was observed for substrate temperatures less than 400 degreesC and for Se/Zn atomic flux ratios higher than 1.00 +/- 0.05.