Background: Neutrophil gelatinase-associated lipocalin (NGAL) serum values have been shown to increase in preeclampsia. The goal of the present study was to evaluate changes in urinary NGAL concentrations during uncomplicated pregnancy and in cases of preeclampsia and hypertension. Methods: Fifty-one pregnant women who developed preeclampsia and 28 diagnosed with essential or gestational hypertension were investigated for urinary NGAL concentrations during pregnancy. As controls, 100 healthy pregnant women with uncomplicated singleton pregnancies were randomly selected. Urinary NGAL as well as urinary creatinine and albumin were measured by a standardized clinical chemistry platform (ARCHITECT®; Abbott Diagnostics, Abbott Park, IL, USA). Results: Urinary NGAL concentrations increased during pregnancy in healthy pregnant women, whereas this increase was not detected in preeclampsia. In order to correct for diuresis, spot urine concentrations were also determined as NGAL/creatinine ratio. NGAL/creatinine ratio in pregnancy week 36-38 was significantly lower in preeclampsia than in healthy pregnant women or pregnant women with hypertension. NGAL urinary concentrations did not correlate with albumin concentration in urine. Conclusions: Urinary NGAL is not a valuable early biomarker for preeclampsia.