Evidence of molecular alterations in the tumour suppressor gene WWOX in benign and malignant bone related lesions of the jaws. WWOX is a tumour suppressor gene altered in various human neoplasms. Deletion of WWOX is associated with bone metabolic defects and development of osteosarcoma in mice. We hypothesized that alterations of this gene are associated with the development of benign and malignant mesenchymal bone related lesions of the jaws. We investigated WWOX mRNA by nested reverse transcription-PCR and direct sequencing and quantitative real-time PCR in two osteosarcoma, two fibrosarcoma, eight ossifying fibroma and two fibrous dysplasia fresh samples. Malignancy was associated with a decreased WWOX mRNA expression. Aberrant transcription pattern was found in five samples; however, the relative quantification (RQ) of the WWOX mRNA in such lesions was not different from those carrying only the wild-type. We provide new evidence of WWOX alterations in osteosarcomas and demonstrate for the first time alterations of this gene in fibrosarcomas as well as in ossifying fibromas of the jaws.