We report three paediatric cases, and summarise the reported experience in two others, with cardiorespiratory failure requiring extracorporeal life support for which supportive pump flows could not be maintained due to abdominal compartment syndrome. In two of our patients, the mechanism of abdominal compartment syndrome was massive intra-abdominal fluid extravasation secondary to sepsis, while in the third, the mechanism was post-traumatic intra-abdominal haemorrhage. Although all three children eventually died, decompressive laparotomy and arrest of haemorrhage in the trauma patient restored venous return and enabled technically adequate extracorporeal life support. In two previously reported cases of sepsis with massive fluid resuscitation resulting in abdominal compartment syndrome, one patient died without attempted decompression, while the other patient survived after peritoneal catheter placement restored venous return. Once correctable causes of inadequate venous cannula drainage have been excluded, abdominal compartment syndrome should be considered in any patient on extracorporeal life support with a taut abdomen and reduced venous return. If abdominal compartment syndrome can be proven or is strongly suspected, there may be a role for selective decompressive laparotomy.