Myasthenia gravis (MG)(1) is an autoimmune disease directed at the neuromuscular junction, and cytokines are thought to contribute to its immunopathogenesis. Interleukin-27 (IL-27)(2) plays a complex and pleiotropic role in immune responses associated with T helper cells. To assess the role of IL-27 in MG, we determined serum IL-27 levels in MG patients (n=32) compared to healthy controls (n=50). The median serum IL-27 level was significantly higher in MG patients (35.947pg/mL) than in controls (19.885pg/mL). Furthermore, serum IL-27 was significantly higher in early onset MG. This study suggests the possibility that IL-27 might contribute to MG pathogenesis or immunoregulation.