The skeleton is one of the common places were many tumors metastasize. Skeletal metastases may profoundly affect the patients' quality of life by making them unable to move freely and help themselves, while in some cases impingement upon the CNS structures can cause neurologic symptoms. Early diagnosis of bone metastases is therefore very important in order to prevent severe debilitating conditions. We review the role of different diagnostic methods available for the detection of bone metastases, as well as their response to treatment: bone scintigraphy, plain films, computed tomography (CT) and magnetic resonance imaging (MRI). The role of positron emission tomography (PET) and PET/CT is also discussed.