Protein and amino acid requirements of the Greater rhea (Rhea americana) have been estimated from growth data available for this species, and assumptions derived with other closely related species. Differences in body weight and growth pattern caused considerable higher protein and amino acid requirements for males compared to females after 3 months of age. Whereas the absolute protein requirement is comparable between males (148 g/day) and females (144.5 g/day) at 50 days of age, 21.8 g/day protein isneeded by males at 500 days of age compared to 12.2 g/day for females. Limitations include the lack of knowledge on feed intake and possible digestive adaptations by Greater rheas. However, estimations could serve as a starting point for direct responsetrials to determine nutrient requirements of the Greater rhea, which could be improved and developed as new information becomes available.