Circulating monocytes are mononuclear cells which are highly specialized in phagocytosis and antigen presentation, secrete a large range of different cytokines, and migrate to the tissues in response to infection and injury. Monocytes can be subdivided into three major subsets: the classical monocytes (CD14+CD16-), the intermediate monocytes (CD14+CD16+) and the non-classical monocytes (CD14-CD16+). It is suggested that classical monocytes differentiate successively into intermediate and non-classical monocytes. We investigated by flow cytometry the proportion and function of circulating monocytes in MG Patients (13 AChR+ MG patients and 10 controls). Gating on the monocyte population, we clearly observed in MG patients a significant decrease of non-classical monocytes defined as CD14-CD16+. This decrease of non-conventional monocytes was further confirmed by gating on CD14-/lowCD16+ CCR2- CD116- to exclude a potential bias due to CD16+ dendritic cells. We also analyzed serum levels in 24 AChR+ MG patients and 16 controls for cytokines known to reflect monocyte activation (sCD14 and sCD163) or cytokines involved in monocyte differentiation, such as GM-CSF, M-CSF, IL-13, IFN-γ. We did not observe any variation in serum levels of sCD14 and sCD163 in MG patients but we observed an imbalance in cytokine cocktail that might influence monocyte differentiation. Altogether, we showed a decrease of non-classical monocytes in AChR+ MG patients. This decrease might be associated with the pathophysiology of MG and need to be further investigated.