Oreochromis niloiicus fingeriings with initial body weight and length ranging from 20 to 39.5g and from 10 to 13.5cm., respectively .were reared in two cement ponds at a density of 4 fish/m". The two cement ponds were divided into five equal divisions (partitions) by nets. Fishes in each partition were fed on one of the experimental diets at 3% of body weight 6 times a week for a period of 130 days.This research was carried out at Al-Kanater AL-Khayria Fish Research Station to study the effect of dietary protein sources on growth of O. niloticus. Growth rate, average daily gain, specific growth rate and feed conversion ratio were determined. The results indicated that the highest growth rate (0.86), highest specific growth rate (0.96), maximum weight gain percentage (250.6%) and the lowest feed conversion ratio (2.37) were obtained for fish fed the formulated diet containing 25% protein, whereas the opposite was found for fish fed wheat bran alone. Results also showed that animal protein diet was better than plant protein diet for tilapia feeding. From the economical point of view,the results indicated that the balanced diet containing 20% protein was the most suitable diet for fish feeding in the cement ponds.