A 57-year-old man presented with abdominal pain following a collapse, with peritonism in his lower abdomen. He was haemodynamically stable, with haemoglobin of 12.6 g/dl. His significant medical history included open bilateral inguinal hernia repairs. CT demonstrated fluid within the abdominal cavity, and an area of stranding lying medially within the left iliac fossa. Ultra-sound guided fluid aspiration demonstrated frank blood. During admission, the patient noted a recurrence of his left inguinal hernia. Laparotomy revealed haemoperitoneum, and a haematoma arising in the left iliac fossa, walled off by mesentery of the sigmoid colon and adherent omentum. The open repair of the recurrent inguinal hernia identified the sac contents to be similar to the omentum. This association implies the omentum had herniated within the inguinal canal, tore or avulsed, resulting in haemorrhage from the proximal omental blood vessel resulting in haemoperitonism.