Primary Gastrointestinal Follicular Lymphoma is very rare. It is considered as an indolent lymphoma, but a complication such as a perforation can increase the morbidity and mortality. We report the case of a 57-years-old man who had a perforation primary follicular lymphoma of the jejunum presenting as aneurismal form. He had peritonitis at his admission, and his abdominal CT revealed a massive pneumoperitoneum and a segmental dilatation of the small intestine. The surgical exploration found a segmental dilatation of the jejunum perforated on its ante-mesenteric side with a large mesenteric lymphadenopathy. Histological and immunohistochimical of the samples shown a jejunal follicular lymphoma. The patient died of heart failure 6 months after his surgery before he has started his chemotherapy. There is no consensus for the treatment of gastrointestinal follicular lymphoma, but chemotherapy is the most common strategy. Surgery is performed for a complication such as a perforation. A complication of a gastrointestinal follicular lymphoma contributes to increase the mortality.