This research was conducted with the aim of evaluating the effect of wheatgrass, which contains chlorophyll and a high percentage of antioxidants such as Vitamin C and selenium in addition to some minerals such as calcium, iron, and magnesium on the biological efficiency and the immune system in white rats. In the present study, 40 rats were divided into 8 groups, each of 5 rats, and it was divided into two experiments I and II with each trial four groups. In Experiment I, 5 rats were fed the basic meal and were used as a   negative control group. The other 15 rats are divided into 3 sub-groups (1, 2 and 3) each fed on the main meal plus wheatgrass at rates of 100,150, and 200 mg, respectively, and then a method of suppressing the immune system was performed at the end of the trial period. In experiment II, animals were immune suppressed by stress treatment as done in experiment I then divided into 4 groups (5 rats each). The first group was served as positive control [Co. (+) ] and fed basal diet only, while the other three groups (4, 5 and 6 ) were served as experimental groups and were fed basal diet and wheatgrass (100, 150 and 200mg). All groups recorded stability in weight at the beginning and at the end of the experiment and in their acquired increase in their weight gained, food efficiency, intake of food as compared to the control negative group, while groups 4, 5 and 6 had the lowest average rate of food intake compared to the positive control. All groups were found to have no change in the relative weight of their spleen and liver. All the experimental groups recorded no change in the percentage of hemoglobin, red blood cells and hematocrit compared to the control group. Also, they showed a decrease in the MCV rate and MCH compared to the control groups. All groups recorded no change in the rate of MCHC and an increase in the rate of RDW% compared to the control. Groups 1, 2 and 3 showed a significant decrease in urea and uric acid compared to the control group. While groups 4, 5 and 6 showed a significant increase in urea compared to the control group. All the experimental groups showed an increase in the level of creatinine compared to the control group.