A hydraulic tensioner with an internal reservoir. The tensioner includes a housing having a sleeve, and a hollow piston slidably received about the sleeve and biased in a protruding direction by a spring. A fluid chamber is defined by the sleeve and the hollow piston. Fluid from an external source flows through a passageway into a reservoir which is located inside the tensioner housing above the fluid chamber. The reservoir is connected to the fluid chamber such that fluid flows from the reservoir through a check valve assembly into the fluid chamber such that the fluid chamber remains filled with fluid.