Background Behcet's disease (BD) is a systemic disorder with a vascular tropism where the vessels might be affected. Venous thrombosis is the most common vascular complication. Among its locations, vena cava thrombosis (VCT) are rare but can be life-threatening.

The purpose of this work is to specify the frequency of VCT in the course of Behcet's disease in morocco and to analyse epidemiological, clinical and therapeutic modalities.

Objectives This retrospective study was conduced in the internal medicine department of the University Hospital IbnRochd of Casablanca, over a period of thirty-five years between 1980 and 2016.

Methods Where included 1618 cases of Behcet's disease, all diagnosed in our service and meeting the diagnosis criteria as defined by the international study group (ISG) for Behcet's disease.

Results 52 patients with VCT – 47 men and 4 women - were gathered during this period, representing a rate of 3.30% of 1572 cases, with a mean age of 35 years (ranges 17–54).

The diagnosis of VCT and BD was concomitant in 10 cases and occurred during the course of the disease in 42 cases after an average of 6 years of evolution.

Among the localization. Inferior VCT is the most frequent localization ( 32 patients, including 15 cases of Budd- Chiari syndrome). The superior VCT was reported in 24 patients, whereas 5 patients had both a superior and inferior VCT.Vena cava thrombosis was associated with deep venous thrombosis (DVT) of the lower limbs in 24 cases and with an aneurysm in 7 cases (pulmonary artery: 4 cases, femoral artery: 2 cases, abdominal aorta; 1 case).

Regarding the therapeutic modalities, 41 patients were under anti-coagulant treatment, 45 patients received corticosteroids and 51 of the patients were under immunosuppressive agents (cyclophosphamide,azathioprine).

The evolution was significantly improved after the introduction of the immunosuppressive therapy, which were firstly initiated in 2006.

Conclusions Vena cava thrombosis in the context of Behcet's disease is a very serious pathology threatening the patient's vital and functional prognosis.

Preventive measures, early diagnosis and effective treatment are the keys to a successful management of such complications' risks.

Disclosure of Interest None declared