A hydraulic coupling for sub sea applications comprises inter-engageable male and female connectors. The male connector defines a male member for receipt in a chamber defined by the female connector. Each connector has a respective check valve for controlling the flow of fluid through internal bores in the connectors. The check valves are actuable by an actuator between an open position in which hydraulic fluid may flow through the respective internal bore and a closed position in which such flow is interrupted, depending on the distance between the first and second check valves. The male and female connectors are moveable between an uncoupled position in which the check valves are in the closed position and a coupled position in which the male and female connectors are engaged and extend along a longitudinal axis with the male member occupying the chamber of the female connector in a sealed relationship. A pair of seals are provided one on the male member and the other on the in the chamber. The seals are arranged so that they seal the chamber at opposite ends by sealing against respective sealing surfaces in the coupled position. The distance between the first and second check valves in the sealing position is such that the actuator urges them to their open positions. The arrangement ensures that seawater between the connectors is allowed to escape before the sealing relationship is established and, upon coupling, the check valves are opened to allow fluid to flow.