Objective: To evaluate the diagnostic convenience of the 2016 European League Against Rheumatism(EULAR)/American College of Rheumatology(ACR)/Pediatric Rheumatology International Trials Organization( PRINTO) classification for macrophage activation syndrome(MAS) in patients with systemic-Juvenile Idiopathic Arthritis(s-JIA). Methods: We performed a retrospective analysis of patients with s-JIA who were admitted to Department of Pediatrics, Hallym Medical Center between 2002. Febrary and 2016. April. The patients with s-JIA were evaluated for MAS using the 2016 classification criteria for MAS. Laboratory findings and clinical features were analyzed. Results: 79(30.0%) out of 263 JIA patients were s-JIA. Among 79 patients with s-JIA, 8(10.1%) were classified as having MAS. The patients who met the diagnostic criteria for 2012 were those with high ferritin levels and fibrinogen tests. And, of the 8 MAS patients, 3(3.7%) were met for the new diagnostic criteria. Conclusion: In the past, MAS needs at least two laboratory criteria or two clinical and/or laboratory criteria. And, bone marrow puncture was necessary in uncertain cases. So, we did bone marrow in 18 cases. However, 2016 classification criteria for MAS, because hemophagocytosis is often absent during the early stages of MAS and its demonstration requires an invasive procedure, the bone marrow test was excepted for the calssification of sJIA-associated MAS. When we applied the new diagnostic criteria, diagnostic rate seemed to be lower than before. Because, in our medical center, the rate of fibrinogen test was significantly lower in the past and recently bone marrow test was excluded. Although new diagnostic criteria simplify the diagnostic process, based on the fact that some tests were missed but MAS could be diagnosed with bone marrow results, bone marrow examination should be done if necessary.