We investigated small-scale hydraulic power actuation systems using a system level analysis, where small-scale refers to systems generating 10 to 100 W output power, to determine whether the high power density advantage of hydraulics holds at small sizes. Hydraulic actuator system power density was analyzed with simple physics models and compared to an equivalent electromechanical system comprised of off-the-shelf components. Calculation results revealed that high operating pressures are needed for small-scale hydraulics to be lighter than the equivalent electromechanical system. The analysis was limited to the actuator and conduit as those are the components that must be located on the mechanism. A complete comparison should add the weight and efficiency of the power supply.