Pustular cutaneous vasculitis results from a heterogeneous group of disorders characterized by pustules on purpuric bases. Although the cause of this group of conditions is diverse, the histopathologic picture of the lesions is the same, showing a Sweet's-like or leukocytoclastic vasculitis. These distinctive lesions may occur in patients with Behçet's syndrome, bowel-associated dermatosis-arthritis syndrome, or chronic gonococcemia. We describe, for the first time, a patient with primary idiopathic cutaneous pustular vasculitis. This patient had evidence of both circulating immune complexes and serum enhancement of neutrophil migration. Extensive evaluation failed to reveal any underlying systemic disease. A classification of the pustular vasculitides is proposed.