The objective of the present study was to analyse whether there is a relationship between the clinical severity at the time of starting transpyloric enteral nutrition (TEN) and the onset of digestive tract complications in critically ill children. Between May 2005 and December 2007, we performed a prospective, observational study with the participation of 209 critically ill children aged between 3 d and 17 years and who received TEN. The characteristics of the nutrition and its tolerance were compared with the paediatric risk of mortality (PRISM), the paediatric index of mortality (PIM) and the paediatric logistic organ dysfunction index (PELOD) at the time of starting the nutrition. Higher PRISM and PELOD scores correlated with a later time of starting enteral nutrition, a longer time to reach the maximum daily energy delivery and a longer duration of the TEN. However, the severity scores did not correlate with the maximum energy delivery achieved. Abdominal distension or excessive gastric residues were observed in 4.7 % of the patients and diarrhoea in 4.3 %. The ability of the severity scores to predict diarrhoea was of 0.67 for PRISM, 0.63 for PELOD and 0.60 for PIM-2.The severity scores were not able to predict other digestive tract complications. Higher scores of clinical severity at the time of starting enteral nutrition correlate with a later initiation of the nutrition, a longer time to reach the maximum energy delivery and a longer duration of TEN. However, their ability to predict digestive tract complications is low.