Abstract Continuous intravenous ( IV ) infusion has been shown to be the best option to administer vancomycin because of its time‐dependent bactericidal activity. Available IV vancomycin dosing guidelines in pediatrics with normal renal function leads to less than 50% of patients achieving a vancomycin serum concentration (Css) in the target range (15–20 mg/L). The primary objective of this study was to prospectively validate an age‐based dosing regimen in pediatric oncology–hematology. The secondary objective was to investigate the influence on Css attainment of different variables. A continuous IV dosing nomogram was built by retrospective study (2000–2010) on Bayesian dosing adjustments performed in 161 patients. This study assessed the prospective validation of this age‐based nomogram and the influence on Css attainment of variables as the gender, underlying disease (oncology or hematology), and hematopoietic stem cell transplantation ( HSCT ) before receiving vancomycin therapy. A total of 94 patients aged from 4.3 months to 17.9 years old with normal renal function were eligible for the prospective validation. Fifty‐five of those patients (58.5%) achieved the target range of vancomycin Css. There was no significant difference between age groups ( P = 0.816) and no influence of gender ( P = 0.500). There was a nonsignificant trend to a better target attainment in oncology patients (69.2% vs. hematology 54.4%, P = 0.142) and patients who did not undergo HSCT (63.3% vs. 33.3%, P = 0.031). This study proposed an age‐based nomogram prospectively validated which near 60% of patients of each age class achieving the target range of Css.