Condensation: Both Gonal-F and Puregon, especially in their high-dosage administration, might inhibit the endometrial cell proliferation in the initial 48-hour culture. After 72-hour culture, Gonal-F persisted the inhibition of the endometrial growth, whereas Puregon reversed its effect to enhance endometrial growth. Objectives: Endometrial proliferation or regeneration during menstrual cycle is regulated by sexual hormones. However, the effect of gonadotropins on the endometrial cell growth remains obscure. Herein, we aimed to investigate the effects of recombinant follicle-stimulating hormones (r-FSHs) (Gonal-F and Puregon) on the proliferation of human endometrial cells in vitro. Materials and Methods: Human endometrial cells (RL95-2 cells) were obtained commercially and cultured in the serum-containing media in the presence of r-FSHs (Gonal-F and Puregon at concentrations of 0. mIU/mL, 200. mIU/mL, 400. mIU/mL, and 600. mIU/mL) up to 72 hours. According to the gonadotropin concentrations, all cultured endometrial cells were divided into four groups: (1) 0. mIU/mL (control); (2) 200. mIU/mL; (3) 400. mIU/mL; and (4) 600. mIU/mL. After 72-hour culture, endometrial cell proliferations were assessed overnight by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The influences of different r-FSH agents and dosages on endometrial cell proliferation in each group were evaluated and compared. Results: In the four Gonal-F groups, the cell absorption (control and 200. mIU/mL, 400. mIU/mL, and 600. mIU/mL Gonal-F) after 24/48/72-hour cultures were as follows: (1) 0.57/0.7/0.82; (2) 0.56/0.66/0.78; (3) 0.55/0.64/0.77; and (4) 0.51/0.61/0.78. After 48 hours, higher dosage of Gonal-F appeared to significantly inhibit the endometrial cell proliferation. After 72-hour culture, all three dosages of Gonal-F appeared to inhibit the endometrial cell proliferation similarly. In Puregon groups, the cell absorptions were as follows: (1) 0.62/0.53/0.62; (2) 0.61/0.5/0.66; (3) 0.61/0.49/0.66; and (4) 0.64/0.49/0.66. Puregon administration displayed initial inhibition and subsequent stimulation effects on the endometrial cells. Conclusions: Both Gonal-F and Puregon, especially in their high-dosage administration, appeared to inhibit the endometrial cell proliferation in the initial 48-hour culture. After 72-hour culture, Gonal-F persisted the inhibition of the endometrium, whereas Puregon reversed its effect by enhancing the endometrial growth. The differences might be because of the different formulations or molecular structures existing between alpha and beta follitropins.