Afive-month feeding trial was conducted to evaluate the effect of eplacement of soybean meal by linseed meal and adding Yucca schidigera powder extract ,methionine and lysine on growth performance and body composition of Nile tilapia, Oreochromis niloticus (L) with an average initial weight of 30.8± 13 g/fish. The experimental* fish were divided into 18 groups and fed on pelleted feed containing each of the plant protein meal- supplemented with Yucca schidigera powder extract at 750 mg kg"1. Methionine (0.5%) and lysine (0.5%) were added to each diet except the control diet (FMC) which was supplemented with yucca only to examine the effect of replacement soybean with linseed meal on growth rate, feed conversion ratio (FCR), protein efficiency ratio (PER) and body composition of reared fish . Three groups of fish were fed on each of six isonitrogenous (25.2% C.P) and isocaloric (4.3 kcal g"1) feed, where the soybean meal (SBM) was replaced with linseed meal (LSM) at a levels of 0%, 25%, 50%, 75% and 100%.The experiment was performed in three concrete ponds and the valume of each was ( 40m3 ) (4 x 10 x 1.0 m , long, width, and height respectively ) . Ponds were divided into six units (6m2) by nets. The experimental fish were stocked at a rate of 10 tilapia/m2 (60 tilapia/unite). After five months of feeding , results revealed that the fish fed on plant protein diets supplemented with Yucca exhibited growth performance not differing significantly from that fish fed on FMC. Linseed levels in the diets were significantly influenced the whole body composition of the Nile tilapia. It has been revealed that increasing level of linseed, increased body moisture content and fat content, while protein content decreased. It was concluded that soybean could be completely replaced by linseed in Nile tilapia diets without adverse effect on growth rate, when diets supplemented with Yucca schidigera.