Abstract: An injection valve arrangement for injecting an auxiliary medium into a combustion chamber of a cylinder of an internal combustion engine in order to reduce the concentration of noxious substances in the exhaust gases of the engine comprises a valve body bounding a first chamber into which the pressure medium is continuously fed through a feed duct and an elongated valve member for controlling the feeding of the auxiliary medium from the first chamber into the combustion chamber of the cylinder and being spring-loaded toward a closed position, in which it prevents the injection of the additional medium. The valve body also bounds a second chamber into which the auxiliary medium is fed, and the pressure prevailing in the second chamber urges the valve member toward the closed position.