Tribulus terrestris extract and 17α-methyltestosterone were added into the diets of red tilapia fry with an initial average weight of 0.02 ± 0.003g and an average length of 0.6 ± 0.012cm to study their effects on sex reversal and gonads histology. Two T. terrestris extract treatments (1 and 2g/kg diet); three hormonal treatments of 17α-methyltestosterone (30, 60 and 100 mg/kg diet) were used in this study and a control group, the study lasted 112 days. Results showed that T. terrestris extract and 17α-MT has a potential effect on directing gonadal sex differentiation of red tilapia towards males depending on the dose applied. The highest male percentage 90% was obtained by 60 mg 17α-MT /kg diet followed by 2g T. terrestris / kg diet (84.40%). Histological examination of the gonads showed a clear deterioration in their structure as a result of hormonal therapy, the intensity of which increased with an increase in the hormonal dose. The effect from using a high dose of T. terrestris was slight. It can be concluded that the addition of T. terrestris extract and 17α-MT to the ration of red tilapia hybrid fry directs the gonads of red tilapia towards males and negatively affects the structure of the gonads.