Introduction: Heterotopic mesenteric ossification is an extremely rare condition, which often follows trauma and is frequently symptomatic. To date, there are no reports in the literature of abdominal compartment syndrome occurring after surgical resection of mesenteric calcification. The present report documents an unusual case of compartment syndrome complicating resection of extensive mesenteric calcification despite abdominal closure with the components-separation technique. Method: A 48-year-old man undergoing components-separation technique for posttraumatic laparostomy hernia repair (ileostomy reversal and sigmoid stricture correction) was found to have extensive heterotopic mesenteric calcification, which needed resection. Results: Resection of the mesenteric calcification was complicated by intraoperative hemorrhage and unplanned small bowel resection. Later the patient developed secondary hemorrhage leading to an abdominal compartment syndrome, which was successfully treated by decompression, hemostasis, and Permacol-assisted laparotomy wound closure. The patient remains symptom-free more than 2 years after surgery. Discussion: The case herein reported gives an account of the rare occurrence of abdominal compartment syndrome following resection of posttraumatic ectopic mesenteric ossifications. It is highly unusual in that it occurred because of “secondary hemorrhage” and despite abdominal closure with the components-separation technique, which had been undertaken precisely to prevent compartment syndrome with direct closure. It therefore highlights the need for continued clinical vigilance in complex posttraumatic cases.