Brown tumor is a focal lesion differentiated from other giant cell tumor by the presence of hyperparathyroidism. These lesions are non-neoplastic and they appear as a mass with partly cystic and partly solid areas. Clinically they are slow growing lesions that can be locally destructive resulting in variety of symptoms such as significant bone swelling, pain and pathological fracture. Here is a female patient of 26 years with brown tumor involving mandible, maxilla and left knee joint.