Abstract Behcet's disease (BD) is a chronic relapsing systemic vasculitis of unknown etiology. BD is very rarely associated with neoplastic diseases. We report the case of a 39-year-old woman who had been treated for BD for 3 years. She presented with relapsing oral and genital lesions and persistent high-grade fever which had lasted for 1 month. The possible cause of the exacerbation of BD and fever in this patient was a mature ovarian teratoma. To our knowledge this is the first report of a patient with BD associated with a ovarian teratoma.