BACKGROUND Adult onset Still's disease is a chronic multisystemic inflammatory disorder characterized by high spiking fever, polyarthralgia and rash. Lymphadenopathy is a prominent feature of adult onset Still's disease and is seen in about 65% of patients. Searching the medical literature using the MEDLINE database from January 1966 through November 2007 we could only find two reported cases of adult onset Still's disease that had progressed to lymphoma. METHODS We describe a woman who was diagnosed with adult onset Still's disease and developed lymphoma 10 months after the onset of her symptoms. She initially presented with fever and arthritis of the knees, ankles and shoulders, along with a nonpruritic skin rash, myalgia and weight loss. On physical examination she was found to have several enlarged anterior cervical lymph nodes and left posterior auricular lymph nodes all of which were non-tender, immobile and rubbery. Excisional biopsy of the cervical lymph nodes was negative for malignancy. Bone marrow biopsy was also negative for malignancy. She was treated with prednisone. She remained in good health until she presented 10 months later with low back pain, dyspnea and weight loss. Work up revealed malignant lymphoma. She was treated with chemotherapy and was doing well until she presented with abdominal pain. Work up revealed a cirrhotic liver and ascites. She then passed away from hepatorenal syndrome 13 years after the diagnosis of lymphoma. To our knowledge, this is the third reported case of such an occurrence. CONCLUSIONS Although the association between adult onset Still's disease and lymphoma has been rarely reported, careful screening for this malignancy in patients suspected to have adult onset Still's disease is warranted.