We present a case of 35-year-old man who was referred to us with a preliminary diagnosis of multiple spinal metastasis. Laboratory studies have shown a high serum alkaline phosphatase and a low bone alkaline phosphatase levels. Spinal magnetic resonance scans demonstrated involvement of T9, T11 and L3 vertebral bodies. The involved vertebrae appeared hypointense on T1- and hyperintense on T2-weighted images and a radionuclide bone scan has shown increased uptake in involved vertebral bodies. A transpedicular open biopsy was considered necessary for accurate diagnosis. Histopathologic evaluation of the specimen revealed typical “mosaic pattern” of Paget’s disease. After surgery, urinary deoxypridinoline and pridinoline levels were tested and were higher than normal. The patient was given oral doses of alendronate, 40 mg per day and follow-up magnetic resonance scans at 6 months and 2 years demonstrated improvement in the signal intensity of the involved vertebral bodies. This case not only shows that Paget’s disease can occur in the setting of low bone AP but also shows that the clinical improvement can be monitored by improvement in magnetic resonance signal.