Adult Still's Disease is a rare systemic inflammatory disease. It is characteristically identified in the young adult, with few cases described in older patients. The aetiology and pathogenesis remain unknown. The absence of uniformly accepted diagnostic criteria may contribute to underdiagnosis. We present a case of 74-year-old patient with fever, polyarthralgia, odynophagia, salmon evanescent rash, elevated inflammatory parameters and serum ferritin. Excluded other diagnostics (infections, neoplasias and other immune diseases), the diagnosis of Adult Still's Disease was assumed. The clinical and analytical improvements with immunosuppressive therapy, and long follow-up without symptomatology, give strength to the diagnosis. We present this case by rarity of this pathology in this age and to illustrate how an apparently banal clinical picture may represent a diagnostic challenge.