Objective To evaluate the reasons of positive MR findings and negative radionuclide bone scan in the spinal metastasis.Methods 68 patients with spinal metastasis were undergone MR scan and radionuclide bone scan.MRI appearances including the site,location and their relation to the cortex of bone were analyzed. The relationship between MRI and radionuclide bone scan appearances were also analyzed.Results 561 lesions were detected by MRI,and only 199 lesions were found by raionuclide(199/561=35.47%).133 lesions located in the bone marrow without cortex erosion were not detected by radionuclide bone scan. The detective ratios of lesions located in the subcortex and through cortex were 25.58%(55/215) and 67.61%(144/213) on radionuclide bone scan respectively. The detective ratios in small lesions (