Abstract: A hydraulic brake lever assembly includes a hollow lever mount accommodating therein a hydraulic pump. Two window openings are respectively formed in opposite sides of a middle section of the lever mount and in communication with an interior space of the lever mount. The hydraulic pump includes an outer cylinder member and an inner bore member arranged inside the outer cylinder member to define a hydraulic fluid chamber therebetween. An in-flow passage is defined in a wall of the inner bore member to communicate a bore defined in the inner bore member. A spring-biased piston is movably received in the bore of the inner bore member. The piston is driven by a driving bar coupled to a handgrip. The outer cylinder member forms in a wall thereof a hole receiving and in threading engagement with a transparent plug that is exposed through each of the window openings.