Hafnium isotopic compositions were measured in Al-depleted and Al-enriched komatiites from the 3450 Ma old Barberton greenstone belt, southern Africa. All samples have initial ϵHf values close to zero. Such values are at variance with the strongly negative or positive values that should be observed if these rocks came from old garnet-depleted or garnet-enriched layers, such as may have formed during the solidification of an ancient terrestrial magma ocean. The garnet fractionation observed in komatiites probably took place during the melting event.