Abstract. If G is the closure of L∞ in exp L2, it is proved that the inclusion between rearrangement invariant spaces E ⊂ F is strictly singular if and only if it is disjointly strictly singular andis not an interpolation space between L∞ and G it is proved that there exists another Marcinkiewicz space M (ψ) M (ϕ) with the property that the M (ψ) and M (ϕ) norms are equivalent on the Rademacher subspace. Applications are given and a question of Milman answered.