Granulomatosis with polyangiitis (GPA) and eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as Wegener's granulomatosis and Churg-Strauss Syndrome respectively, are systemic granulomatous vasculitides affecting small- and medium-sized blood vessels. Both GPA and EGPA are included within the group of antineutrophilic cytoplasmic antibodies (ANCA)-associated vasculitides, on the basis of the detection of such autoantibodies in a significant proportion of affected patients. Two main settings of GPA, possibly overlapping each other, are recognized: a localized form, which is limited to the upper airways but is highly relapsing and refractory, and a diffuse form, which is initially more severe but then less commonly recurrent. In EGPA, a prodromic phase characterized by asthma and rhino-sinusitis is followed by an eosinophilic phase, marked by peripheral eosinophilia, and then by a vasculitic phase, in which skin lesions are a prominent feature together with peripheral neuropathy and renal involvement. Polymorphic cutaneous manifestations can occur during the course of both GPA and EGPA, and include palpable purpura, livedo reticularis, papules, nodules, vesiculo-bullae and necrotic-ulcerative lesions most commonly involving the lower extremities; pyoderma gangrenosum-like ulcers and lesions resembling erythema multiforme have been described in GPA and EGPA, respectively. Oral involvement is not uncommon in GPA and may manifest as nonspecific erosive lesions or as a hyperplastic gingivitis named strawberry gingivitis. Considering that skin involvement is common in ANCA-associated vasculitides and may also be their presenting sign, the role of dermatologist is crucial in the early diagnosis of these forms as well as of vasculitis in general.