The magnetic property of the pristine and germanium-doped (10, 0) boron-nitride (BN) nanotube has been studied using a DFT-LSDA method. The germanium substitution for either a single boron or single nitrogen atom yields a spin-polarized, almost dispersionless pi bands within the original band gap and net magnetic moment is 1 mu(B). The. at band originates from the local structural deformation in the vicinity of germanium atom. Contrast to the theoretical models based on carbon or silicon-doped BN nanotubes, substituting a nitrogen atom with germanium atom results in three pairs of in-gap states which indicates more extended nanotube deformation than those previously studied. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.