Acute complications requiring admission to pediatric intensive care unit (PICU) are frequent for children with cancer. Our objective was to determine early prognostic factors of mortality in a cohort of children with cancer hospitalized in PICU for acute complications and particularly to assess whether the delay before admission to a PICU is an early predictor of mortality. We conduct a retrospective multicenter analysis. All patients transferred in PICU for acute complications between January 2002 and December 2012 were included. One-month mortality of the 224 patients analyzed was 24.5%. Delay before PICU admission was a significant prognostic factor of 1-month mortality with nonsurvivors experiencing a longer median delay than survivors (24 vs. 12 h, respectively, P<0.05). Time from diagnosis to PICU admission (P<0.001), hematopoietic stem cell transplant (P<0.05), the duration of neutropenia (P<0.01), infection type (P<0.001), number of organ dysfunctions (P<0.001), and reaching any grade 4 toxicity before PICU admission (P<0.001) also affected mortality rate at 1-month post-PICU discharge. In the multivariate analysis, only reaching any grade 4 toxicity before PICU admission influenced 1-month mortality (odds ratio, 2.30; 95% confidence interval, 1.07-4.96; P<0.05). These results suggest that PICU admission before severe impairment leads to a better outcome for children with cancer.