Introduction. Adult-onset Still's disease is a rare systemic autoinflammatory disorder of unknown etiology, characterized by persistent fever, maculopapular skin rash, and arthritis or arthralgia. This triad of symptoms is usually accompanied by lymphadenopathy, hepatosplenomegaly, and various systemic manifestations. In the absence of adequate therapy, the disease course might become life-threatening, with complications such as macrophage activation syndrome, hemorrhagic alveolitis, disseminated intravascular coagulation syndrome. Case report. We present a case of adult-onset Still's disease, misdiagnosed and treated initially as Hodgkin's lymphoma. The further examination revealed a complex of lymphadenopathy, skin changes, articular syndrome, making possible to reject the diagnosis of Hodgkin's lymphoma and to diagnose adult Still's disease. In the context of this case, we present potential difficulties in the analysis of clinical and laboratory data, histology results, and the differential diagnosis difficulties of this disease. Conclusions. The diagnosis of adult Still's disease requires a vast spectrum of clinical and morphological manifestations of the disease, that will make possible the correct interpretation of the clinical symptoms and laboratory tests, avoiding unnecessary examinations, and will speed up the diagnosis time. © 2021 Balkan Medical Union. All rights reserved.