Abstract： AIM To study the expression of IL-2 mRNA in rat normal anteriorpituitary. METHODS Total RNA was extracted from rats' normal anterior pituitary tissues and primary cultured cells in vitro. Using the two-step RT-PCR technique, we amplified a DNA fragment in comparatively the same length as that of IL-2 mRNA. Through DNA agarose gel electrophoresis, the fragment was purified and then connected with pGEM-T easy plasmid by the T4 ligase. The connected plasmid was transformed into the E.coli cells.The transformed cells were planted in the Amp+ LB culture medium and cultured for 10～14 h. The positive clones were selected and then the DNA sequencing was conducted. RESULTS The DNA sequence was the same as that of the IL-2 gene fragment. Therefore, there existed IL-2 mRNA in rats' normal anterior pituitary tissues and cultured cells. CONCLUSION It is proved, for the first time, that IL-2 not only exists in the tissues of pituitary adenoma, but is also expressed in the normal pituitary tissues.