Abstract: A flow control valve assembly for an electro-rheological (ER) fluid has an inlet port, an outlet port and a flow path for ER fluid extending between the inlet and outlet ports. A flow control valve is disposed in the flow path and includes a resilient diaphragm, which is acted upon by pressure in the flow path and which is moveable towards and away from the free end of a hollow boss. A flow restrictor in the form of an annular passage defined by electrodes is disposed in the flow path upstream of the flow control valve. An electric field is applied to the ER fluid as it passes between the electrodes to enable control of the resistance to flow of the ER fluid therethrough, thereby enabling control of the pressure drop across the diaphragm. A bypass passage defining a pressure relief valve is disposed downstream of the flow restrictor and permits flow between the inlet and outlet ports when the flow control valve is closed.