Budd-Chiari syndrome (BCS) is a rare disease characterized by the obstruction of hepatic venous outflow due to occlusion of the hepatic vein (HV) or the inferior vena cava (IVC). The pathophysiology of IVC and HV membranous transformation, which can form in isolation or simultaneously, remains unclear in patients with combined-type BCS. Here we report three cases of patients with BCS demonstrating conversion from HV-type to combined-type. Three patients with only HV-type BCS underwent percutaneous balloon angioplasty (PTA) of the obstructed HV. During follow up, membranous transformation of the IVC was observed. This condition was subsequently treated with PTA of the IVC. These cases demonstrate that HV-type BCS may convert to combined-type BCS.