Internal hernias are defined as the protrusion of abdominal viscera through an aperture in the intraperitoneal recesses, they are considered as a rare cause of intestinal obstruction. The paraduodenal hernias are the most common type of congenital hernia especially the left-sided ones. We report a case of a 46 year-old man presenting a left paraduodenal hernia with acute small bowel obstruction, which was firstly (preoperatively) assigned to a tumoral cause.