Epitaxial wurtzite aluminum nitride (AlN) and gallium nitride (GaN) films have been grown on Si(1 1 1) by plasma-assisted molecular beam epitaxy (PA-MBE). Two-dimensional growth (2DG) of single-crystalline AlN films is achieved on Si(1 1 1) near stoichiometric supply of aluminum and atomic nitrogen. Two distinct categories of AlN-surface reconstructions have been observed. GaN films exhibit 1×1 high-energy electron diffraction (RHEED) pattern if grown between 650°C and 770°C substrate temperature on AlN buffers. Stable Ga- and N-adlayer-induced surface reconstructions have been studied below 600°C after the growth. The X-ray diffraction (XRD) pattern show sharp and well separated (0 0 0 l) reflections of wurtzite GaN and AlN indicating complete texture with GaN[0 0 0 1]‖AlN[0 0 01]‖Si[1 1 1]. From the determined GaN lattice constant complete strain relaxation can be concluded which is further confirmed by the temperature-dependent photoluminescence (PL) investigations.