Daily or serial evaluation of multiple organ dysfunction syndrome (MODS) scores may provide useful information. We aimed to validate the daily (d) PELOD-2 score using the set of seven days proposed with the previous version of the score. In all consecutive patients admitted to nine pediatric intensive care units (PICUs) we prospectively measured the dPELOD-2 score at day 1, 2, 5, 8, 12, 16, and 18. PICU mortality was used as the outcome dependent variable. The discriminant power of the dPELOD-2 scores was estimated using the area under the ROC curve and the calibration using the Hosmer-Lemeshow chi-square test. We used a logistic regression to investigate the relationship between the dPELOD-2 scores and outcome, and between the change in PELOD-2 score from day 1 and outcome. We included 3669 patients (median age 15.5 months, mortality rate 6.1%, median length of PICU stay 3 days). Median dPELOD-2 scores were significantly higher in nonsurvivors than in survivors (p < 0.0001). The dPELOD-2 score was available at least at day 2 in 2057 patients: among the 796 patients without MODS on day 1, 186 (23.3%) acquired the syndrome during their PICU stay (mortality 4.9% vs. 0.3% among the 610 who did not; p < 0.0001). Among the 1261 patients with MODS on day 1, the syndrome worsened in 157 (12.4%) and remained unchanged or improved in 1104 (87.6%) (mortality 22.9% vs. 6.6%; p < 0.0001). The AUC of the dPELOD-2 scores ranged from 0.75 (95% CI: 0.67-0.83) to 0.89 (95% CI: 0.86-0.91). The calibration was good with a chi-square test between 13.5 (p = 0.06) and 0.9 (p = 0.99). The PELOD-2 score on day 1 was a significant prognostic factor; the serial evaluation of the change in the dPELOD-2 score from day1, adjusted for baseline value, demonstrated a significant odds ratio of death for each of the 7 days. This study suggests that the progression of the severity of organ dysfunctions can be evaluated by measuring the dPELOD-2 score during a set of 7 days in PICU, providing useful information on outcome in critically ill children. Its external validation would be useful.