To investigate expression levels of serum Th17-related cytokines in patients with childhood-onset myasthenia gravis(CMG). Methods: Sixty patients with CMG were recruited to the CMG group, and 50 age-matched healthy controls were recruited to the HC group. Serum sample was taken from subjects in both groups. Serum titers of IL-23, IL-12/23p40, and IL-17A were quantified by ELISA. Results: Compared with HC group, the levels of IL-23, IL-12/23p40, and IL-17A in CMG group were remarkably increased (P<0.05). Conclusion: The levels of serum Th17-related cytokines were significantly increased in patients with childhood-onset myasthenia gravis, suggesting that it might be involved in the pathogenesis of the disease