Juvenile dermatomyositis is a multisystemic autoimmune disease with uncertain etiology. Both innate immunity and adaptive immunity play a role on the pathogenesis of the disease. Selective immunoglobulin A deficiency is the most common primary immunodeficiency. Association between immunoglobulin A deficiency and autoimmune diseases including few juvenile dermatomyositis patients have been reported. A previously healthy 15-year old girl was diagnosed with juvenile dermatomyositis according to Bohan and Peter criteria and selective immunoglobulin A deficiency due to the low level of immunoglobulin A (<6 mg/dl). After 3 months of immunosuppressive treatment, her physical examination revealed no muscle weakness, no rashes, and normal muscle enzyme levels. While she has been treated with low dose methylprednisolone and subcutaneous methotrexate, muscle strength and muscle enzymes remained in normal levels at 12 months follow-up. Our knowledge about the co-occurrence of immunodeficiency and autoimmunity emerge that patients diagnosed with autoimmunity should have investigations for immunodeficiency or vice versa.