Kawasaki disease is a systemic vasculitis that manifests itself in many ways. Infants may present as atypical cases and commonly experience severe inflammatory changes. The two cases that are presented here highlight unusual severity and pathology. Patient 1 was a three-month-old infant with atypical Kawasaki disease who developed gangrenous lesions, and coronary and extracoronary artery aneurysms. Multiorgan failure ensued with diffuse cardiac and extracardiac aneurysms and thromboses at autopsy. Patient 2 was a five-month-old infant with Kawasaki disease, cholangitis and peripheral gangrene. Severe coronary artery aneurysms developed and he died following a myocardial infarction, despite multiple doses of intravenous immunoglobulin, acetylsalicylic acid (ASA) and corticosteroids. There is a higher occurrence of atypical disease and more severe vasculitis in infants with Kawasaki disease. Pathological changes are described, including coronary and extracardiac lesions. Patient 1 shows extensive peripheral gangrene and widespread aneurysms, and patient 2 illustrates severe cardiac complications with diffuse organ inflammation. Therapies including intravenous immunoglobulin, ASA, corticosteroids and antithrombotics are reviewed.