Vasculitides and aneurysm formation are well-known complications in Wiskott-Aldrich syndrome (WAS), most often appearing later in life, usually in second decade. The authors report the case of a 5-month-old boy with a genetically and phenotypically severe Wiskott-Aldrich syndrome and sequential formation and spontaneous thrombosis of hepatic aneurysms. This case demonstrates that aneurysm formation may develop early in the course of severe WAS phenotypes. Because of the progressive nature of these manifestations, surgical or interventional procedures are not advisable. Early allogeneic hematopoietic stem cell transplantation (HSCT) should be considered before the manifestation of irreversible organ damage.