A bicycle hydraulic operating system includes first and second actuating devices and a hydraulic operated device. The first actuating device includes a first operating member, a first master cylinder and a first master piston. The first master piston moves in the first master cylinder in response to operation of the first operating member. The second actuating device includes a second operating member, a second master cylinder and a second master piston. The second master piston moves in the second master cylinder in response to operation of the second operating member. The hydraulic operated device includes a slave cylinder and a slave piston that is movably arranged in the slave cylinder. The slave cylinder has a slave fluid port that is connected to first and second fluid ports of the first and second master cylinders. Operation of either of the first and second operating members moves the slave piston.