A high pressure fluid coupling assembly comprises a nipple with a neck to be held in a yoke, which is pulled towards a socket box by a lever mechanism. When the nipple is pulled into complete engagement with the socket, the final downward movement of the lever pushes a locking plate into locking engagement with the distal ends of guide bolts, evenly distributed about the nipple and extending from the yoke and sliding through the socket box to the locking plate, which is in contact with the side of the socket box facing away from the yoke.