We report a case of Behçet syndrome in a young male who presented with fever, oral and genital ulcerations and weight loss. Investigations revealed elevated inflammatory markers and extensive venous thrombosis of the renal vein, inferior vena cava and segmental and subsegmental pulmonary embolisms. He was found to have an intracardiac thrombus in the right atrium and pulmonary nodules. He was diagnosed with Behçet syndrome and was treated with corticosteroids, azathioprine and colchicine. He underwent right atrial thrombus extirpative surgery, and he had a patent foramen ovale, which was closed. Postoperatively, warfarin was started, and infliximab was added to his treatment. Behçet syndrome should be considered early in cases with unexplained venous thrombosis if the patient has other typical clinical features. Fever in Behçet syndrome is typically associated with vascular involvement. Vascular and cardiac involvement is associated with high morbidity and mortality. Therefore, early diagnosis can improve prognosis.