This is a report of an early onset AChR-and MuSK-positive myasthenia gravis. The double seropositivity was detected at the onset of the disease and persisted during 3.5 years follow-up despite the chronic immunotherapy and thymectomy. It is the second reported case of this rare immunological coexistence with sufficient follow-up and available clinical details. At the detection of double positive AChR and MuSK Abs, the treating physician often feels unsecure about the optimal treatment strategy and the long-term prognosis. The detailed clinical record and the long observation of these rare cases, are mandatory for best management in clinical practice.