Problems in diagnosis of bone tumors in routine laboratories concern very rare tumors, differentiation between chondroma and low grade chondrosarcoma, the recognition of lesions containing multinucleated giant cells, lesions with secondary cysts simulating iuvenile or aneurysmal bone cyst and sometimes the discrimination of callus from osteosarcoma. Real misdiagnoses are done in ossifying pseudotumors interpreted as osteosarcoma, metaphyseal fibrous defect confound with giant cell tumor and chondroblastoma misdiagnosed as giant cell tumor or osteosarcoma. All these mistakes are avoidable if the clinical and radiological features, especially age and exact site in bone studied on the x-rays, are taken into consideration.