In Budd-chiari syndrome (BCS), obstruction of the hepatic venous outflow tract occurs at a site from the small hepatic veins to the junction of the inferior vena cava with the right atrium, and this syndrome can have various causes. Remarkably, BCS can be classified as primary or secondary; primary BCS is caused by venous thrombus or phlebitis, while secondary BCS is due to venous compression or invasion of an extrinsic lesion, such as a tumor, abscess, or cyst. Antiphospholipid syndrome (APS) is an acquired cause of primary BCS. A 24-year-old man, with complaints of abdominal pain, abdominand anorexia starting three months earlier, was admitted to Rasht Razi Hospital. The patient's pain did not relate to feeding, defecation and positioning. The patient had nausea and vomiting half an hour after feeding. He also mentioned a weight loss of about 5 kg and also,had blood pressure. He had no history of smoking, alcohol and opiums and had not any specific illness in his family. Due to abdominal distension and hepatosplenomegaly, an ultrasound examination was performed for the patient, ascites were diagnosed and the patient was subjected to ascites fluid paracentesis. High gradient of albumin and low protein were reported. The patient was first examined for cardiac examination and heart echocardiography and other examinations were reported as normal. A CT scan of the abdomen, pelvic and doppler ultrasonography was performed that showed ascites and enlargement of the caudate lobe. The findings were compatible with BCS. The diagnosis of BCS was confirmed by a hemodynamic study, and further investigation for the cause of BCS was positive. Antinuclear antibodies, deficiency of protein C and S were detected. LA was not present and aCL (IgM, IgG) were positive. Moreover, serology was negative for hepatitis B or C and serum protein electrophoresis was demonstrated high levels of gamma globulin. We concluded that the patient had chronic BCS secondary to APS in association with autoimmune hepatitis. Ultimately, the patient was treated with prednisolone 60 mg/daily and warfarin, and was referred to a transplantation-equipped center for liver transplantation. In conclusion, BCS, although infrequent, is not a rare complication in patients with APS and may be the first clinical manifestation of this syndrome. In this patient, BCS caused by the initiation of AIH and secondary APS.