A study was made to identify sex differentiation  in parents andfries of Oreochromis aureus using RAPD- PCR and squash techniques. Fishes were collected from the experiment shared in program for producing “supermales ZZ" in Egypt. The trial of sex reversal for feminization of sexually undifferentiated progeny was conducted using 17-β ethynylestradiol as a feminizingstimulating agent.  Oral administration of powdered feed containing 400 and 800 mg/kg were tested for 30 days in Central Laboratory for Aquaculture Research in Abassa (CLAR).Upon termination of the experiment, average weight and length  have increased using  high dose. In contrast, the survival rate was  increased in low dose (400 mg/kg) than high dose (800 mg/kg). Its effect was highly detectable among fry that were orally fed on 800-mg/kg hormone-treated feeds for 30 days. The  mean percentage of phenotypic females was  94%± 2.7 in the second season, females generated progeny including mean percentage of phenotypic males was 69%±4.6 while female, inter sex and non differential percentages were 26% ±3.8, 3%± 1.5  and 2%±0.7  respectively. the sex  differentiated  have been using applied  squash  method  and  RAPD-PCR ,  Squash  method   illustrated  that from every  10 fishes,  9  individuals  were converted into super male (ZZ) .  In RAPD -PCR, seven  primers were used and they showed  different  bands patterns between male and female . The  total  number  of DNA fragment band was  35 in maleparents and 33 in femaleparents. While, numbers of DNA fragment bands produced  by seven  primers were 33 and 35 in adult converted females and fries converted females.  Total numbers of DNA fragment bands were 35 and 40 in males and 33 and 35 in female. These molecular markers detected by primers (A14, B13and C05) could be used as markers associated with male or female differentiation.