Acute monoarthritis is a common situation in orthopedic emergency where the patient presents with typical inflamed joint. It is hard to clinically distinguish inflammatory arthritis of bacterial origin from monoarthritis attacks of gout disease. If these two situations, which are the most common causes of acute monoarthritis, are misdiagnosed, outcomes might be catastrophic and costly. Synovial fluid analysis is the most reliable method for confirming the diagnosis although it might not always lead to definitive diagnosis. If there is clinical suspicion for crystal arthropathy, repeated examinations may provide benefits for confirming the diagnosis.