Background Equine neonatal sepsis can be challenging to diagnose and prognosticate. Neutrophil gelatinase-associated lipocalin (NGAL), a new marker of renal damage and inflammation, can potentially be helpful. Objectives To evaluate NGAL in neonatal foals with sepsis, and assess its relation to outcome. Animals Foals ≤ 14 days, with admission blood analysis and stored serum. Methods NGAL was measured on stored serum from 91 foals. Foals were scored for sepsis and survival and categorized according to sepsis status (septic, sick non-septic, healthy, and uncertain sepsis status) and outcome groups (survivors and non-survivors). The septic foals were further sub-categorized according to severity (normal sepsis, severe sepsis and septic shock). A Kruskal-Wallis test was used to compare serum NGAL concentrations in survivors and non-survivors, in the sepsis status groups, and in the sepsis severity groups. Optimal cut-off values for serum NGAL concentrations to diagnose sepsis and outcome were determined with receiver operating characteristic (ROC) curves. NGAL was compared to creatinine and SAA. Results Median serum NGAL concentrations were significantly higher in septic than non-septic foals. However, serum NGAL concentrations did not differ between sepsis severity subgroups. Serum NGAL concentrations were significantly lower in survivors than in non-survivors. Optimal cut-off values of serum NGAL concentrations were 455 μg/L (sensitivity 71.4%, specificity 100%) and 1104 μg/L (sensitivity 39.3%, specificity 95.2%) for predicting sepsis and non-survival, respectively. NGAL correlated to SAA, but not to creatinine. NGAL performed similarly to SAA to diagnose sepsis. Conclusion Serum NGAL concentrations may be useful for diagnosing sepsis and predicting outcome.