Background: Thymomas, which could be intrapulmonary or mediastinal, benign or invasive have been reported to be associated with SLE in 34 cases in literature. However, it is more commonly associated with myasthenia gravis. MacKechnie et al demonstrated 14 cases of coexistence of thymoma, myasthenia gravis (MG), erythroblastopenic anemia and systemic lupus erythetmatosus (SLE) in a patient. And in these 14 patients, only 6 among them presented the coexistence of SLE, myasthenia gravis and thymoma. Pathogenetic link has been reported and the coexistence of these three diseases appears in a decreased incidence as reported by few cases in literature worldwide. Objective: To present a case of Primary Intrapulmonary Thymoma, Systemic Lupus Erythematosus and Myasthenia Gravis in One Patient and the pathogenic link among these diseases. Setting: De La Salle University Medical Center, a tertiary hospital in Dasmarinas, Cavite. Case: A 35 year old female, diagnosed with systemic lupus erythematosus developed a left lung mass on the fifth year of illness. Intrapulmonary thymoma was confirmed with a CT Scan guided biopsy of the mass and immunohistochemistry staining. On the seventh year of illness, patient presented with bilateral lower extremity weakness and bilateral ptosis and was treated for myasthenia gravis.Significance: To discuss prognosis of a lupus patient with intrapulmonary thymoma who developed myasthenia gravis.