To investigate the characteristics of patients with adult-onset Still's disease (AOSD), serum cytokines and chemokines were measured to examine their associations with systemic manifestations of AOSD, especially hemophagocytic syndrome (HPS). Nineteen patients diagnosed with AOSD were enrolled. Serial serum samples were obtained from patients with AOSD in both active and inactive stages and controls. The concentrations of cytokines and chemokines, including IL-18, soluble IL-2 receptor (sIL-2R), CX3CL1, CXCL8, CXCL10, CCL2, and CCL3, were determined using enzyme-linked immunosorbent assay. Multivariate analysis was used to evaluate the correlations among serum chemokine levels, disease activity, and the clinical features of AOSD. Significantly higher serum levels of all cytokines and chemokines were observed in patients with active, untreated AOSD than in controls. The level of CX3CL1, but not other chemokines, was elevated in AOSD patients and was positively correlated with clinical activity and the levels of CRP, ferritin, IL-18, and sIL-2R. Among the 19 patients with AOSD, four patients also had HPS. Serum CX3CL1 and ferritin were significantly higher in AOSD patients with HPS than in those without HPS. The serum CX3CL1 level may be used as a clinical marker to assess the disease activity of AOSD, and high serum CX3CL1 and ferritin in patients with AOSD reflected the presence of HPS. The association between the chemokine profile and distinct clinical manifestations or various patterns of disease progression indicates that the pathogenesis of AOSD is heterogeneous.