A-plane InN film has been grown on r-plane sapphire substrate by MOCVD without any buffer. X-ray omega/2 theta scan confirms that only wurtzite-type InN was grown. The in-plane orientation relationship between a-plane InN and r-plane sapphire is < 0001 >(InN)//[(1) over bar 101](sapphire) and [(1) over bar 100](InN)//[11 (2) over bar0](Sapphire) deduced from selected area diffraction. Atomic force microscopy reveals that no stripe features appear on surface of the a-plane InN film, which is different from that of a-plane GaN grown on r-plane sapphire where stripes along [0 0 0 1] direction appear on the surface. The difference originates from the different growth mode of InN and GaN. In addition, photoluminescence and absorption spectra show that our a-plane InN has a narrow band gap of 0.7 eV, which is similar to that of c-plane InN film grown by the same system. (c) 2008 Elsevier B.V. All rights reserved.