High levels of serum leptin (LPT) were reported in adult patients with sepsis and a protective role was suggested. LPT was determined in sera from 55 children with severe sepsis at admission (0 h), 6, 24 and 48 h. LPT levels were higher at 0 h than at 24 h (2.80 vs 1.61 ng/ml; p= 0.009) and a negative correlation was found with IL‐13 (p= 0.009), and granulocyte counts (p= 0.035), but not with other factors. Infants younger than 12 mo of age had higher LPT levels than older infants (5.88 vs 2.38 ng/ml; p= 0.0005). The increase in LPT levels was higher in non‐survivor patients than in survivors, with a maximum difference at 24 h (5.30 vs 1.45 ng/ml; p= 0.0042). However, LPT levels were not associated with shock, multiorgan failure or the severity score. Children who died showed higher percentiles of weight than survivors (p= 0.025). A subgroup with higher LPT (