Systemic lupus erythematosus (SLE) is an autoimmune disorder with multiorgan involvement, more than half of SLE patients develop lupus nephritis in progression of their disease. ANCA associated vasculitis (AAV) are a group of systemic autoimmune diseases affecting small to medium-sized vessels. Systemic lupus erythematosus and small-sized vessel vasculitis are usually two distinguishable autoimmune diseases. The presence of ANCA, particularly c-ANCA in SLE is not common. We report a case of SLE associated to c-ANCA. Our objective is to discuss clinical significance, etiopathogenic mechanism and management of this association. This book is addressed to a wide audience of doctors.