Abstract: This study is presented to test the effect of injecting a mixture of Serine/Threonine or Glycine amino acids to determine and measure the changes in mRNAs expression for TGF 2, 3 within the mouse testes and the ovaries. Male (n = 30) and female (n = 30) mice (CD-1 strain) were injected, once a day for 5 days, with 0.2 mL Saline (control), 0.2 mL Saline with a mixture of Serine/Threonine (test) containing 0.26 οΏ½g L Threonine, 0.13 οΏ½g L Serine or 38 ng Glycine (Test). Total RNA was extracted and transferred on to a nylon membrane then probed with 32P-lebelled cDNA probes. The expression of mRNA for TGF 2 increased in male mice while there were no differences in female mice. This study shows that TGF 2, 3 are expressed both in the ovary and testis and their expressions were increased by the injection of Serine/Threonine or glycine.