A leaf seal is proposed for effecting a seal between two coaxial and relatively rotating components. The seal has an annular pack of stacked leaves, the pack being mountable to a first one of the components at root portions of the leaves and extending towards the other component such that end edges of the leaves cooperate to define a seal surface of the pack which is presented for air-riding interaction with a surface of the other component during relative rotation between the components such that, in use, a pressure drop is maintained axially across the pack. The seal surface of the pack incorporates a plurality of hydrodynamic lift-generating recesses spaced circumferentially around the pack. Each said recess extends circumferentially across a plurality of adjacent leaves in the pack, each of which leaves being spaced radially from said surface of the other component along at least part of its end edge.