(1) The nutrition of the eastern grey kangaroo and the wallaroo was studied in two areas in the New England Tablelands of eastern Australia. The pastures on one of the areas had been extensively improved by the use of fertilizers and the introduction of exotic grasses, whereas the other area was largely unimproved with the pastures dominated by tussock grasses. (2) The quality of food eaten by the two species was higher on the improved area than on the unimproved area. However, stomach fill indices indicated that animals on the unimproved area were eating a greater quantity of food than were those on the improved area. (3) Grey kangaroos on the unimproved area were recycling a greater proportion of urea to the gut than were those on the improved area. For wallaroos the pattern of seasonal change in the level of urea recycling differed on the two areas. (4) Energy appears to be a limiting resource on both areas.