Run-of-river type hydroelectric power plants generate electrical energy by using a certain portion of the available flow in the river. A computer program called MINI-HPD is developed to perform the hydraulic design of run-of river plants. This program, which runs under the Windows operating system, is developed in C# programming language. MINI-HPD is capable ofperforming hydraulic design of structural components of diversion weir with lateral intake and overflow spillway, canal, forebay, and penstock. In addition, it can determine the optimum design discharge, optimum installed capacity, and optimum penstock diameter for this type of plants. It is desired to have quick successive runs under various scenarios and combinations of relevant parameters. An application is presented to illustrate the use of the program.