BACKGROUND AND OBJECTIVE: In transfusion dependent thalassemic patients, if their transfusion requirement increases over 20 ml/Kg of whole blood, splenectomy is indicated. Portal vein thrombosis (PVT) is one of life threatening complications of splenectomy. Follow up of splenectomized patients in order to the earliest diagnosis and treatment of PVT can improve the survival of them. The aim of this study was to assess the frequency of PVT in splenectomised thalassaemia patients.METHODS: This cross sectional study was performed on 63 splenectomized thalassemic patients who referred to Yahyanejad hospital of Babol for follow up during 8 years (from June 2001 to June 2009). Patients were evaluated for age, gender, type of operation, splenectomy indication, spleen size, operation duration, clinical manifestation, PVT frequency, and time interval of splenectomy and occurrence of PVT, Color Doppler Sonography findings, PVT treatment and follow-up.FINDINGS: PVT was identified in 6 (9.5%) patients (4 females and 2 males) (95% CI: 2.1-17). The mean time of patient’s follow up was 5.26±2.7 years. Average of surgery duration was 2.72±0.8 hours. The average of time interval of splenectomy and occurrence of PVT was 229±176 days. All of the patients treated by low molecular weight heparin during hospitalization and discharged by Warfarin for 4 months. Two patients received propranolol at the time of discharge, too.CONCLUSION: The results of this study show that early diagnosis of PVT by following up the patients who splenectomised and treatment of PVT with anticoagulant can reduce the adverse of this complication.