We are very grateful to the Servicio Hidráulico and Servicio de Carreteras de Obras Publicas of the Canarian Government for permission to study the cores of boreholes, and to Dn. José Esteve for his great help. We really appreciate the constructive comments of R.A. Duncan which significantly improved the original text. The authors want to thank Drs. C. Laj and C. Kissel (CFR, CEACNRS) for valuable comments and sugestions during the realisation of this work and also Dr J. Channel. Dr. V. Soler (EVC. CSIC) helped greatly with the paleomagnetic sampling and analysis. N. Max and Y. Comette (CFR) and E. Rodríguez Valdés and C. Duch (EVC) for their technical support.The combined use of accurate radiometric dating and magnetic stratigraphy can be applied to define the main stages of the building of oceanic volcanic islands. This method has been successfully applied on the island of El Hierro, the westernmost island of the Canaries Archipelago. For the emerged part of this island, built in the last 1.2 Ma, magnetic stratigraphy and mapping show the presence of four consecutive subchrons. K-Ar dating of eighteen samples in stratigraphic sequences using an unspiked technique produced ages consistent with the general volcanic stratigraphy. The ages show that the magnetic polarity zones correlate to the upper part of the Matuyama and to the Brunhes chrons. The Jaramillo normal polarity subchron of the upper part of the Matuyama reverse polarity Chron is recorded in one of the lava sequences. The lower limit of this event is constrained by two ages of 1.04 ± 0.02 Ma and one of 1.05 ± 0.02 Ma, close to the value deduced from the astronomically tuned magnetic polarity time scale (APTS). The volcanic history can be summarised by two consecutive main basaltic volcanic edifices: the El Tinor, active during the upper part of the Matuyama Chron and the El Golfo edifice, constructed during the Brunhes Chron.This work has been supported by the Spanish DGICYT (PB92-0119), a NATO (CRG 940609) research project and the french CEA and CNRS /INSU (C.F.R. contribution No. 1769) as part of a DBT project.Peer reviewed