Little is known about the epidemiology of systemic vasculitis in South American countries. The aim of this study is to compare the prevalence of systemic vasculitides in two vasculitis referral centers from Brazil and Peru. A cross-sectional study was performed and all patients above 18 years of age, with at least 6 months of follow-up and who met classification or diagnosis criteria for the most common forms of vasculitis, were included. A total of 562 patients with systemic vasculitis were analyzed, 345 (61.4%) from Brazil and 217 (38.6%) from Peru. The frequency of Behçet’s disease (37.9% vs. 1.8%; p < 0.0001), Takayasu arteritis (TAK) (25.2% vs. 6.9%; p < 0.0001), and giant cell arteritis (9.8% vs. 0.9%; p < 0.0001) was higher in the Brazilian center than the Peruvian one. On the other hand, the frequency of microscopic polyangiitis (MPA) (67.3% vs. 2.8%; p < 0.0001) and renal-limited vasculitis (2.8% vs. 0.0%; p = 0.009) was higher in the Peruvian center. No differences were found concerning other forms of vasculitis. At diagnosis, Brazilian patients with TAK, granulomatosis with polyangiitis, and MPA were younger than Peruvian patients. Epidemiologic differences in the frequency of systemic vasculitis are observed between a vasculitis referral center from Brazil and another from Peru.Key Points• Significant differences are observed regarding the epidemiologic profile of systemic vasculitis between Brazil and Peru.• MPA is the predominant form of vasculitis in Peru while BD and TAK are the most frequent forms of vasculitis in Brazil.• The age at diagnosis of TAK, MPA, and GPA was lower in Brazilian patients than in Peruvian patients.