RESUMEN Dos cuerpos porfiriticos de composicion riodacitica, localizados en el sector central del Macizo de Santander (Cordillera Oriental), fueron datados mediante el metodo U-Pb, usando la tecnica LA-MC-ICPMS: Laser Ablation Multicollector-Inductively-Coupled-Plasma Mass Spectrometer . Las edades obtenidas (8.4 ±0.2 y 9.0 ± 0.2 Ma), evidencian una etapa magmatica durante el Mioceno Tardio (Tortoniano), la cual tuvo lugar durante la orogenia Andina. La identificacion de este pulso magmatico, ademas de aportar nuevos elementos sobre la historia geologica del Macizo de Santander, merece especial atencion, desde el punto de vista de la exploracion de depositos minerales, teniendo en cuenta que rocas de estas caracteristicas y edad se relacionan con la formacion de importantes yacimientos magmatico-hidrotermales, tal como se ha reconocido en otras regiones del extenso sistema orogenico Andino. Palabras claves: Edades U-Pb, Macizo de Santander, Rocas Porfiriticas, Mioceno. ABSTRACT Two riodacite porphyry bodies, located in the central sector of the Santander Massif (Cordillera Oriental), were dated by U-Pb method, using the LA-MC-ICPMS technique: Multicollector-Laser Ablation- Inductively Coupled Plasma-Mass Spectrometer . The obtained ages (8.4 ± 0.2 and 9.0 ± 0.2 Ma), evidences a magmatic phase during the Late Miocene (Tortoniano), which took place during the Andean Orogeny. The identification of this magmatic pulse, in addition to provide new information on the geological history of the Santander Massif, deserves special attention, from the point of view of mineral deposit exploration, considering that rocks with the same age and features are related to the formation of important magmatic-hydrothermal deposits, as has been recognized in other regions of the Andean orogenic system. Keywords: U-Pb ages, Santander Massif, Porphyry Rocks, Miocene.