An eight-month-old, male domestic shorthair kitten developed progressive abdominal distension over a six-week period. Abdominocentesis revealed a fluid with high protein (3.8 g/dl) and moderate cellularity. Infectious, cardiovascular, and neoplastic causes of posthepatic obstruction were ruled out. Partial obstruction and stenosis of the caudal vena cava (CVC) at the level of the diaphragm were detected on a contrast venogram. Exploratory surgery revealed a fibrous, web-like membrane at the site of obstruction. Resection of the stenotic segment of the CVC was not possible because of the junction of the left hepatic veins and CVC just caudal to the lesion. A 3 by 6-mm, oval Dacron patch graft was sutured into the venotomy site. Postoperative complications included fever and leukocytosis, eosinophilic pleural effusion, and transient congestive heart failure associated with volume overload. The cat is normal 16 months after surgery, with no recurrence of ascites. This is the first reported case of Budd-Chiari syndrome (BCS) in a domestic kitten. Documented herein is the first successful treatment of BCS in a small animal using a vascular, prosthetic patch graft.