Fuzzy logic control is so-called artificial intelligence because control laws are designed by human decision, not by deterministic numerical calculations. This paper investigates the effectiveness of a fuzzy logic control method in vibration control with a semi-active MR fluid actuator. The system to be controlled is a simply supported beam to which is applied a persistent excitation. Numerical simulation and experimental tests are performed. Three semi-active control laws, one deterministic and two fuzzy-logic, were applied and compared on the basis of vibration control performance and energy consumption. These controllers are compared to the baseline fully-on control where the MR fluids are energized so that the actuator performs as a tuned passive damper. Simulation and experimental data were examined.