BACKGROUND Adult-onset Still's Disease (AOSD) is a rare systemic inflammatory disease accompanied by a triad of spiking fever, maculopapular exanthema, and arthralgia. To date, there is no definite laboratory or imaging test available for diagnosing AOSD, and the diagnosis is one of exclusion, which can be very challenging. CASE REPORT We report on the case of a 53-year-old female who presented with fever, arthralgia, and abdominal pain. Her initial laboratory tests showed elevated AST and ALT, and normal leukocytes with bandemia. During her hospitalization, we evaluated the patient for other potential differential diagnoses. After an extensive workup, the patient was diagnosed with AOSD based on Yamaguchi criteria. Her serum ferritin levels were measured and found to be markedly elevated, which is a non-specific finding in AOSD patients. CONCLUSIONS This case highlights the important role of a detailed history and physical examination for timely diagnosis of AOSD to prevent complications and improve patient's prognosis.