The focus of this paper is on the experimental validation of a mathematical model that was developed for the flow of magnetorheological (MR) fluids through the annular gap in a MR damper. Unlike previous work by other researchers, which approximate the flow of the MR fluid through this annulus as a flow of fluid through two infinitely wide parallel plates, the model presented represents accurately the annular flow. In this paper, the mathematical model is validated via experimental testing and analysis of a double-tube MR damper fabricated at the University of Manchester, UK. The experimental setup and the procedures for executing the tests on the MR damper according to established standards for the testing of conventional automotive dampers are given. This involved sets of many isofrequency sinusoidal tests of various displacement amplitudes. Predictions from theoretical simulations based on the mathematical model are validated using the data collected from the experiments. It was found that the modeling procedure represents the MR damper very satisfactorily.