Cutaneous vasculitis (CV), a condition characterized by palpable purpura and nonspecific histopathologic findings, presents a diagnostic and therapeutic challenge because it may be a primary disorder or it may be a cutaneous manifestation of another entity, such as systemic necrotizing vasculitis, connective tissue disease, systemic bacterial infection, or malignancy. We studied 303 unselected patients (172 adults and 131 children) with CV to assess the disease associations and etiologic factors, to identify the frequency of primary and secondary CV in different age-groups, and to characterize features that help to distinguish between primary and secondary CV. Of the 131 children, 130 had primary CV: Henoch-Schönlein purpura (HSP) in 116 and hypersensitivity vasculitis (HV) in 14. In contrast, of the 172 adults, only 120 had primary CV: HSP in 39, HV in 70, and essential mixed cryoglobulinemia in 11. CV was a manifestation of systemic necrotizing vasculitis in 23 adults (polyarteritis nodosa in 17, Wegener granulomatosis in 4, and Churg-Strauss syndrome in 2). CV was secondary to other processes in 29 adults: in 20 patients CV was associated with connective tissue disease or another autoimmune or rheumatic disease, in 5 patients CV was a manifestation of severe bacterial infection, especially bacterial endocarditis (4 cases), and in the other 4 patients CV was the presenting symptom of an underlying malignancy. The patients for whom CV was a manifestation of systemic necrotizing vasculitis or secondary to a connective tissue disease, severe bacterial infection, or malignancy had clinical and laboratory data suggestive of the associated disorder. The clinical picture and outcome of primary CV in both children and adults were benign. By contrast, the prognosis of patients with CV in the context of systemic necrotizing vasculitis or secondary to other entities depended on the primary process. Given the different disease association in children and adults, we propose a simple diagnostic workup in children with CV. By contrast the diagnostic approach in adults with CV should be more cautious and the workup more extensive. The early differentiation between primary CV, secondary CV, and CV presenting as a symptom of systemic necrotizing vasculitis, especially in adults, is of paramount importance for an adequate diagnosis and appropriate treatment.