Downpull on tunnel gates installed in the intake structure of a hydroelectric power plant was studied experimentally using a hydraulic model. The pressure distribution on the gate lip surface was measured, and the lip downpull was evaluated by surface-area integration of the measured pressure distribution. An easy to use lip downpull coefficient was defined as a function of the lip angle and gate opening. The lip downpull coefficient function is linked to a one-dimensional mathematical model of unsteady flow in the intake-penstock system. The model is based on the integral energy and continuity equations. Overflow through the gate spacings is also included in the model to compute the water level in the gate shaft and to evaluate the downpull component on the top face of the gate. Time-dependent calculation of the total downpull force acting on a closing gate is exemplified. The total downpull is also measured by the direct weighing method for fixed and closing gates. Predictions of the mathematical model compare favorably with the downpull obtained from the direct weighing method.