In this paper we present a synthesis on the Toarcian/Aalenian (Lias/Dogger) boundary in the Iberian Peninsula. We have selected in each domain the most representative areas and sections in which this boundary is represented: Fuentelsaz and Moyuela sections in the Iberian Cordillera, Sierra de Ricote and Cerro Mendez in the Betic Cordillera, and Sao Giao in the Lusitanian Basin. In these areas the succession across the Toarcian/Aalenian boundary is represented mainly by pelagic grey marl-marly limestone rhythmites, which contain abundant and characteristic ammonites. The standard ammonite zones of Aalensis (Mactra, Aalensis and Buckmani Subzones) for the uppermost Upper Toarcian, and Opalinum (Opalinum and Comptum Subzones) in the Lower Aalenian are recognised and characterised. Although the ammonite assemblages of the Betic Cordillera are typical of the Mediterranean province, and the Iberian and Lusitanian basins constitute a Sub-Mediterranean one, the ammonite assemblages are similar in the three basins, with the only significant difference being that phylloceratids and lytoceratids are abundant in the Betic domain and are scarcer in the other basins.