A preliminary study of the protein requirements of the Malaysian giant freshwater prawn (Macrobrachium rosenbergii De Man) was conducted by dispensing pelleted diets consiting of varying levels of protein (10.7, 23.2, 37.5, 45.6, 49.2, 50.9, 55.4, 57.2 and 59.9%) in the form of fishmeal incorporated with other feed ingredients. Protein deficient and rich diets demonstrated growth rates that were not promising. An optimum weight gain and food conversion was observed in a diet amended with 47.3% carbohydrate. The amended carbohydrate levels in the diet also had an important bearing on the composition of the diet because it was the prime energy source. It was dound that food conversion values correlated very well with the growth rates of the experimental animals but not with that of protein efficiency ratio. [Author's abstract].