Traumatic lumbar hernias are rare but important injuries to diagnose in blunt abdominal trauma, both because of delayed complications of the hernia itself and because of well-documented association with bowel and mesenteric injuries. No study to our knowledge has determined whether specific features of the hernia-size of the wall defect, inferior or superior location, or the side of the hernia-bear any predictive value on the presence of underlying bowel and mesenteric injury. A retrospective query of the radiology information system yielded 21 patients with lumbar hernias which were diagnosed on CT. These were reviewed by three radiologists to confirm the presence of an acute lumbar hernia and to determine the size and location of the hernia. The patients' medical records were reviewed to determine the presence of operatively confirmed bowel and/or mesenteric injuries, which occurred in 52 % of patients. A significant (p<0.001) difference was found in the frequency of bowel and/or mesenteric injury with hernia defects greater than 4.0 cm (100 %) and those less than 4.0 cm (17 %). Larger hernias also resulted in more procedures (p=0.042) and a trend towards longer ICU stay, but no difference in injury severity score (ISS) or overall hospital stay. No significant difference was seen in the frequency of bowel and/or mesenteric injuries based on side or location of the hernia, though distal colonic injuries were more commonly seen with left-sided hernias (50 %) compared to right-sided hernias (18 %). Although based on a small patient population, these results suggest that larger traumatic lumbar hernias warrant particularly close evaluation for an underlying bowel and/or mesenteric injury.