Abstract: A control valve, which consists of a body (1) provided with flow-through channels (2, 3) and of a closing member (5) arranged rotatably in the body in an expansion (4) of the channel, the rotation shaft of which is eccentric in relation to the sealing surfaces of the closing member and the seal of the body. In an open position of the valve a circular flow is formed around the closing member between a wall of the body and the closing member (5), the main flow passage of which circular flow is located in a channel between the inner surface of the body and the upstream edge (16) of the closing member. The closing member (5) has an extension (17) in its upstream edge (16) in the open position, which extension in an initial phase of the opening reduces the cross-sectional area of the main flow passage.