Purpose The goal of this study was to compare the sensitivity of MRI and scintigraphy for detecting metastatic bone disease involving the axial skeleton. Patients and Methods A total of 59 patients (58 women and 1 man, age range 28-83 years, mean age 53.0 years) with histopathologically proven breast cancer during a 15-month period (between April 2003 and January 2004) were included in the study. All the patients underwent scintigraphy and MRI examinations for staging, follow-up, or evaluation of bone pain. Results MR imaging revealed 59 metastases in 59 patients (sensitivity, 95%; specificity, 100%; positive predictive value, 100%). Four lesions detected by MRI were classified as of uncertain origin (grade 2) and 36 lesions were regarded as definitely benign (grade 1). Scintigraphy revealed 44 metastases in 59 patients (sensitivity, 70%; specificity, 94%; positive predictive value, 95%). A total of 29 lesions were considered as of uncertain origin (grade 2), and 26 lesions were regarded as definitely benign (grade 1). About five lesions were graded as grade 2 in scintigraphy, while MRI graded them as degeneration or benign compression (Grade 1). For 11 lesions the same grade was regarded in both MRI and scintigraphy. Two lesions graded as grade 3, and eleven lesions graded as grade 2 in scintigraphy demonstrated no pathological signal intensity in MRI. In total, 18 lesions with no activity in scintigraphy were graded as grade 3 lesions in MRI. Conclusion MRI is more sensitive than scintigraphy in the detection of bone metastases. MRI appears to be able to screen patients more effectively than scintigraphy if the spine and pelvis are included because metastases merely outside the axial skeleton are rare.