Abstract. A boundary backward Harnack inequality is proved for positive solutions of second order parabolic equations in non-divergence form in a bounded cylinder Q = Ω × (0, T ) which vanish on ∂xQ = ∂Ω × (0, T ), where Ω is a bounded Lipschitz domain in R n . This inequality is applied to the proof of the Hölder continuity of the quotient of two positive solutions vanishing on a portion of ∂xQ.