A speech valve comprises a generally cylindrical body and a closure member which is slidably movable within the body between a closed position and an open position. The valve body and the closure member are formed of a rigid, smooth material which is resistant to the growth of biofilm such as a ceramic. A particular suitable ceramic is partially stabilised zirconia. The valve body is provided with an outer sleeve which is provided with radially outward extending annular flanges, which are used to retain the speech valve in a fistula between the oesophagus and the trachea.