Abstract: A downhole sealing apparatus for location in a downhole tubular includes a ball and a downhole seat. The ball may comprise a rigid core and a deformable covering. The ball is translatable downhole towards the seat, the ball and the seat having an open first configuration and a sealing second configuration. In the open first configuration the ball and seat are spaced apart such that fluid may flow through the seat. In the sealing second configuration the ball and the seat are in sealing engagement and the ball is deformed to maintain the sealing engagement with the seat in response to a differential pressure acting in a first axial direction and in response to a differential pressure acting in an opposite second axial direction.