Myasthenia gravis (MG) is an autoimmune condition that involves acetylcholine receptors in the nerve endings that causes progressive muscular weakness and atrophy. In the recent reports, some autoimmune conditions can occur together either coincidental or having causative relationships. There has been many reports on systemic lupus erythematosus (SLE) in association with MG in approximately 2-8% of cases. But there are only three reports on the “triple case”; a case of psoriasis, MG, and SLE in one patient. Herein, we report on this rare concomitant autoimmune condition. A 60-year-old woman visited our clinic with chief complaint of hyperkeratosis of palmoplantar area. She had been on the treatment of MG since 1996. In 2009, she felt dryness of eye and mouth which made her visit rheumatology clinic, and it turned out to be SLE on the laboratory and clinical examinations. Skin biopsy result of patient’s palm is consistent with psoriasis. She treated with phototherapy and oral acitretin for 2 months and no treatment after all. She started oral hydroxychloroquine for SLE. Interestingly, the psoriasis lesion was alleviated even on the hydroxychloroquine.