The seasonal variation in the plant morphological part composition of the dict of Impala in the Sengwa Wildlife Research Area, Rhodesia, was determined by the analysis of rumen content samples from shot animals. The grass species composition of the diet was examined by microscopic identification of grass fragments found in the rumens. The seasonal variation in the dicotyledonous species composition of the diet was studied by direct observation of feeding animals. The protein contents of the rumen contents and faeces were used as measures of diet quality. In the wet season, grass was selected in preference to dicotyledonous plants, and grass leaf was the preferred plant part. In the late wet and early dry seasons, forbs were the principal food. The proportion of woody dicotyledons in the diet was at a maximum in the mid-dry season, when diet quality was at a minimum. Diet quality was directly related to the proportion of grass in the diet. Female Impala had a significantly higher quality diet than males, probably as a result of differential habitat selection.