Budd-Chiari syndrome (BCS) is a rare but severe liver disorder, with low incidence and prevalence in the general population. The incidence reported in the literature ranges from 0.2 to 4.1 cases per million inhabitants per year, with an estimated prevalence of 2.4-7.7 per million inhabitants in Asian countries and of 1.4-4.0 per million inhabitants in Western countries. A predominance of females was reported in the West (52-69%), while in Asian studies males were more frequently affected (48-70%). Patients with BCS tend to be younger than patients with splanchnic vein thrombosis in other sites or venous thromboembolism, with wide variability reported in different countries (e.g. Pakistan, Nepal, Egypt mid-twenties vs USA, Australia, Italy and Denmark in the late-40s/early-50s). Finally, prevalence of BCS in patients with different risk factors (such as myeloproliferative neoplasm, paroxysmal nocturnal haemoglobinuria, Behçet’s disease or liver diseases) is highly variable.