Objectives We evaluated the three-dimensional (3D) micro-architecture of subchondral trabecular (Tb) bone in osteoarthritis (OA). Due to high signal-to-noise ratio and high resolution, micro-computed tomography (micro-CT) by synchrotron radiation is considered as the gold standard for bone micro-architecture imaging. Design Subchondral bone were extracted from femoral heads in OA cases in areas without cartilage (OAc−; n=6) and in adjacent areas with cartilage (OAc+; n=6) and compared to eight subchondral bone cores from osteoporosis cases (OP). The voxel size of images was 10.13 μm. We measured the bone volume fraction (BV/TV) and morphological parameters: Tb thickness (TbTh), Tb spacing (TbSp), Tb number (TbN), and bone surface/bone volume (BS/BV). The degree of anisotropy (DA), the connectivity by the Euler number and the degree of mineralization (DM) were equally assessed. Results BV/TV and morphological parameters showed significant differences between OAc− and OP samples (P<0.01 except TbTh: P<0.05) and between OAc− and OAc+ (0.05