Background: Vancomycin dosing remains a challenge in the pediatric population, due to its high pharmacokinetic variability. This variability increases in patients with cancer, cystic fibrosis or septic shock. Since 2020, the target pharmacokinetic/pharmacodynamic (PK/ PD) recommendation for Staphylococcus aureus infections is an area under the curve on the minimum inhibitory concentration (AUC0-24h/ 0-24h / MIC) between 400-600 mg*h/L; rejecting the basal level between 15-20 mu g/ml. Taking into account the pharmacokinetic changes of pediatric oncology patients, it is evaluated whether the PK/PD objective is achieved with the usual doses of vancomycin. Aim: : To determine the correlation between the initial dose of vancomycin, with the achievement of PK/PD target in pediatric oncology patients. Design: Observational, descriptive and retrospective study, in which pediatric oncology patients who had received treatment with intravenous vancomycin and who had plasma levels monitored according to the protocol of the Dr. Exequiel Gonz & aacute;lez Cortes Hospital were included. The study period included from July 2018 to December 2021. The Precise PK program was used to calculate PK/PD parameters and the R studio software was used for statistical analysis. Results: A total of 59 patients with a median age of 7,5 years were included; The most common type of cancer was acute lymphoblastic leukemia. With initial doses of 60 mg/kg/day, 45.7% of patients achieved the PK/PD objective of an AUC0-24h/MIC 0-24h /MIC between 400-600 mg*h /L. A good correlation was found between the valley level values and the AUC 0-24h ; with a Spearman correlation r value of 0,8. Conclusions: With the dose of 60 mg/kg/day, less than half of oncology patients achieve the PK/PD parameter established for vancomycin. Furthermore, it was observed that there is a good correlation between Cvalley and AUC0-24h/MIC, 0-24h /MIC, which could be considered a useful element in predicting therapeutic success.