For a study, researchers sought to compare the performance of a Doppler-based resistive index (RI) and a semi-quantitative evaluation of renal perfusion using color-Doppler (SQP) to predict de novo AKI in a subgroup of critically ill patients who did not have AKI at the time of admission. This was an ancillary analysis of a multicenter prospective cohort study. The study included consecutive ICU patients who required mechanical ventilation. Renal Doppler was used during ICU admission. On day 3, the diagnostic performance of RI and SQP in predicting de novo AKI was evaluated. The prospective cohort included 118 patients who did not have AKI at study inclusion. About 34 patients (29%) developed AKI. RI (0.64 UI [0.57–0.70] vs. 0.67 [0.62–0.70] in the no AKI and de novo AKI groups, P=0.177) and SQP (2 [2, 3] vs. 2 [1–3] in the no AKI and de novo AKI groups, P=0.061) were not associated with AKI occurrence. Overall, RI and SQP performed poorly in predicting de novo AKI, with the area under the ROC curves of 0.60 (95% CI 0.49–0.65) and 0.58 (95% CI 0.47–0.60), respectively. After controlling for confounders, similar results were obtained. These findings support the poor performance of Doppler-based indices in predicting ICU patients’ renal prognosis.