Growth of group-III nitrides was carried out on zirconium diboride (ZrB2) (0 0 0 1) substrates for the first time. ZrB2 is a semi-metal compound and have a hexagonal crystal structure. The a-axis lattice constant of ZrB2 is 3.169 Angstrom, which is almost lattice-matched to GaN and AlN. GaN and AlN were grown on mirror-polislied ZrB2 (0 0 0 1) substrate directly by molecular beam epitaxy using elemental Al and Ga, and radio frequency plasma-excited active nitrogen. Epitaxial growth was confirmed by in situ reflection high-energy electron diffraction observation and X-ray diffraction pole-figure measurement. The surface morphology of 1.4 mum-thick GaN layer was rough. On the other hand, that of 0.9 mum-thick AlN layer was specular. (C) 2002 Elsevier Science B.V. All rights reserved.