(Abstract) New Caledonia has an exceptionallydiverse and unique ﬂora, and there is growing con-cern about the impacts of introduced wild rusa deer on native forests. The diets of free-ranging rusadeer from two native forest sites were studied us-ing rumen content analysis. Samples ( n= 61) froma sclerophyll forest site consisted principally of graminoids (64.6 ± 4.4% dry weight), mainly nativegrass, but the proportion of woody species increasedduring the dry season. In the rumen samples fromthe rainforest site (n= 56), woody species werethe predominant plants (61.9 ± 3.7% dry weight),and the composition of the diet was more constant across seasons. Most of the food items found couldnot be identiﬁed to species level, but it is estimatedthat native plants represent 40–60% of rusa deer diet. Although more work is needed to assess diet preferences and impacts of rusa deer, we suggest thatthey represent a potentially important threat to somenative plant species in New Caledonia.