Systemic lupus erythematosus (SLE) is a disease with wide range of signs and symptoms. SLE patients have increased infective diathesis, and infections are a very important cause of death in these patients. Infections can sometimes mimic the signs and symptoms of SLE. Thus, it is important to recognize that infection can induce a lupus flare-up or can be difficult to distinguish from a lupus flare-up. We describe a 36-year-old female patient with SLE, who presented with skin lesions and pancytopenia, and clinical manifestations similar to a flare-up of SLE. Bone marrow examination revealed infection with Mycobacterium avium complex (MAC). The patient had no history or clinical evidence of pulmonary involvement. This patient is the first case of invasive bone marrow MAC infection in SLE. With this unique case, we would like to emphasize that SLE patients can also be infected by non-tuberculous mycobacteria, and that bone marrow examination for tuberculosis as well as for non-tuberculosis mycobacteria should be considered in SLE patients with refractory pancytopenia. Lupus (2010) 19, 323-326.