Secondary ion mass spectrometry (SIMS) U-Pb geochronology of zircons from high-pressure granulite units within the allochthonous complexes of the northwestern Iberian Variscan belt illustrates the complexity of dating high-pressure events using the U-Pb chronometer. Zircons from four rocks belonging to the high-pressure (P), high-temperature (T) units were dated by SIMS. A gabbro body with preserved igneous texture within the Órdenes Complex high-P granulites yielded a crystallization age of ca. 515 Ma. A high-P mafic granulite within the same unit contained zircons that had U-Pb ages clustered around 387 Ma, and it preserved no record...