This review covers all aspects of the selective catalytic reduction of nitrogen oxides with hydrocarbons (HC-SCR) over zeolite catalysts, mainly from the viewpoint of their potential for a practical application in exhaust gases from lean-burn engines. Emphasis is placed on HC-SCR over metal-containing zeolites with the exception of copper zeolites. Other items which are addressed are the combination of various metals on zeolites, combined exhaust gas purification systems and mechanistic considerations. (C) 1999 Elsevier Science B.V. All rights reserved.