Autoimmune lymphoproliferative syndrome (ALPS) is an uncommon disorder of Fas-mediated apoptosis that results in impaired lymphocyte death and, therefore, disturbed immune homeostasis. Besides presentation with lymphadenopathy and splenomegaly, patients with ALPS have a high incidence of autoimmune phenomena. To our knowledge, this is the first description of polyarteritis nodosa that includes numerous arterial aneurysms in a child with ALPS. Active vasculitis resolved after allogeneic hematopoietic stem cell transplantation. This report of polyarteritis nodosa associated with human ALPS supports previous findings in Fas-deficient mouse models that frequently develop vasculitic manifestations and suggests that apoptotic defects of lymphocytes may play a role in the pathophysiology of systemic vasculitis. Thus, patients with ALPS might be more susceptible to autoimmune vessel inflammation. This case furthermore emphasizes that even rare autoimmune manifestations should be considered and investigated in patients with immunodeficiencies, because that might help in planning treatment strategies for these patients.