Summary: The one-atmosphere experimental melting and crystallization relations of some basic lavas of Réunion Island, Indian Ocean, are investigated. They comprise products of the extinct volcano Piton des Neiges and the active volcano Piton de la Fournaise. New data and interpretations are presented for the 1939 oceanite and its contained glass, originally described by Lacroix (1939a). The liquidus v. iron enrichment curves for these Réunion lavas fall about 20 °C above those of the lavas of Kilauea, Hawaii. The primitive liquid reaching the surface contained about 10 % MgO.