Objective: To study the effect of insulin on the expression of luteinizing hormone human chorionic gonadotropin receptor(LH/hCG
receptor) of cultured porcine theca cells and look into the possible mechanism of the arrest of follicular growth in polycystic ovary syndrome(POS). Methods: The primary model of cultured porcine theca cells in vitro was established and the cells were treated differently. The level of LH/hCG receptor in the cells was checked by Western blot and cell immuno histochemistry methods. Results: The level of LH/hCG receptor in the cells of group FSH+LH+INS(6598±388)(0.353±0.013) was significantly higher than that of group FSH+LH(2237±395) (0.287 ±0.009), P <0.01 by Western blot and cell immunohistochemistry. The expression of LH/hCG receptor in the cells of group FSH+LH+INS showed 6×10 3, 5×10 3, 3.5×10 3 while group FSH+LH showed only 6×10 3. Conclusion: Insulin enhanced the expression of LH/hCG receptor of cultured porcine theca cells. Hyperinsulinemia may enhance the expression of LH/hCG receptor so as to lose the regularing during menstrical period and probably the arrest of follicular growth in patients with PCOS implicated with hyperinsulinemia.