Two new dopant-related defects which are similar to one another have been found by ESR in vanadium-doped and molybdenum-doped zinc tungstate single crystals. These defects resemble the centre (an electron associated with an oxygen vacancy) reported earlier for electron-irradiated undoped . However, the new centres are significantly modified by a perturbing vanadium or molybdenum dopant ion which substitutes for a tungsten cation neighbouring the trapped electron.