INTRODUCCIÓN: Los índices plaquetarios: volumen plaquetario medio (VPM), ancho de distribución plaquetaria (ADP) y porcentaje de plaquetas grandes (%PG) tienen buena correlación con la etiología de la trombocitopenia en estudios realizados en adultos. OBJETIVO: Determinar las características de los índices plaquetarios en población pediátrica con trombocitopenia y su posible correlación etiológica. METODOLOGÍA: Estudio de prueba diagnóstica observacional analítico. Pacientes entre 6 meses y 18 años ingresados en un período de 18 meses con trombocitopenia [Formula]. RESULTADOS: 54 pacientes: 18 (33,3%) con púrpura trombocitopénica inmune (PTI) y 36 (66,7%) con leucemia aguda (LA), edad media para PTI 7,4 años y 6,8 para LA, valores de ADP con media de 15,08 fL en PTI y 10,73 para LA, la media del VPM para PTI 11,7 fL y de 9,8 fL para LA y %PG la media para PTI 38,26 % vs 24,97% para LA; las diferencias de los tres índices para cada una de las enfermedades fueron estadísticamente significativas (p=0,00). Las curvas de Característica Operativa del Receptor (ROC) de los índices plaquetarios fueron parámetros suficientes para distinguir las causas de trombocitopenia: VPM y %PG con un área bajo la curva de 0,89 y 0,88 y ADP 0,903. CONCLUSIONES: los índices fueron útiles para el acercamiento inicial al diagnóstico diferencial de trombocitopenias en niños.Abstract. INTRODUCTION: Platelet-derived indices (Mean Platelet Volume/MPV; Platelet size Deviation Width/PDW; and Platelet Large Cell-Percentage/PLCP) are well established correlates for diagnosis of Thrombocytopenia in adult-based research. OBJECTIVE: To determine the values of platelet-derived indices in a pediatric population with diagnostic of Thrombocytopenia and their etiologic correlation. METHODS: Analytic Observational Diagnostic-Test Study. The population for this analytical study were pediatric patients between 6 months to 18 years-old subjects who had thrombocytopenia [Formula], the study period was over 18 months. RESULTS: For 54 subjects: 18 (33,3%) were diagnosed with Immune Thrombocytopenic Purpure (ITP) and 36 (66,7%) diagnosed with Acute Leukemia (AL); mean age was 7,4 years and 6,8 years for ITP and AL, respectively; mean PDW values were 15,08 fL and 10,73 for ITP and AL, respectively; mean MPV was 11,7 fL and 9,8 fL for ITP and AL, respectively. Mean PLCP was 38,26% and 24,97% for ITP and AL, respectively. Differences of this three distinct platelet indices between ITP an AL were statistically significant (p=0,00). The area under the curve of the Receiver Operating Characteristics (ROC) for platelet-derived indices showed that they were adequate for defining the causes of Thrombocytopenia: MPV and PLCP with an area under the curve (AUC) of 0,89 and 0,88, respectively and PLCP with an AUC of 0,903. CONCLUSIONS: Platelet-derived indices could be useful in the initial approach for differential diagnostic of pediatric patients with thrombocytopenia.