The authors report a case of severe spontaneous hemorrhage in a patient who underwent surgical repair of an upper umbilical ventral hernia with placement of a polypropylene mesh. On the third postoperative day the patient experienced bleeding in the properitoneal space (above and below the mesh), which spread up to and along the retroperitoneal area, causing severe hypovolemic shock. Postoperative investigations finally identified a virus as the cause of the complication.