To assess the association between urine output (UO), arterial lactate levels (LL) and lactate clearance with haemodynamic instability and death in very low birth weight (VLBW) preterm in the transitional period. Retrospective cohort study with VLBW newborns born in 2016 and 2017, excluding those with malformations and without data. We evaluated 254 preterm infants with a total of 482 lactate levels measured in the first 72 h. Areas under the curve (AUC) were calculated for receiver-operator characteristics (ROC) curves of UO and LL (alone and combined) and of lactate clearance for prediction of haemodynamic instability and death. All AUC were below 0.80. Sensitivity and specificity were also not very good. Although patients with poor outcomes had lactate levels higher than those with good outcomes, discrimination was poor. UO and LL and lactate clearance were not good predictors of haemodynamic instability or death within 10 days of life. What is Known • It is already established that blood pressure is not a good marker for haemodynamic stability in the preterm infant. • Others clinical parameters, albeit are largely used, are not fully reliable as well. What is New • In our study we tried to determine the sensibility and specificity of urine output and arterial lactate and also the lactate clearance. • All AUC were below 0.80. Sensitivity and specificity were also not very good. Although patients with poor outcomes had lactate levels higher than those with good outcomes, discrimination was poor.