Epitaxial InN layers were deposited on MgAl2O4 (1 1 1) substrates by microwave-excited metalorganic vapor-phase epitaxy. The crystallographic orientation relationships between the InN layer and MgAl2O4 (1 1 1) were InN (0 0 . 1)\\MgAl2O4 (1 1 1) and InN [1 1 . 0]\\MgAl2O4 [1 0 0]. The full-width at half-maximum of the X-ray rocking curve of 97 arcsec was obtained on MgAl2O4 (1 1 1).