用小鼠抗早孕实验，观察甲氨蝶呤（ＭＴＸ）单用和合并用药的抗早孕作用。小鼠于妊娠ｄ７分别一次ｓｃＭＴＸ８，２４和７２ｍｇ·ｋｇ－１可引起胚胎死亡，妊娠ｄ１３死亡率分别为１８０％，５５５％和６０３％。给药后测定血清孕酮水平，妊娠ｄ９未发现明显改变，妊娠ｄ１３其水平明显降低。小鼠于妊娠ｄ７～９注射ＭＴＸ２４ｍｇ·ｋｇ－１连续３ｄ引起胚胎全部死亡。ｈＣＧ和孕酮可拮抗ＭＴＸ的抗早孕作用。ＲＵ４８６可增强ＭＴＸ的抗早孕作用，提示两药合用抗早孕有协同作用。 Anti-early pregnancy experiments with mice to observe methotrexate (MTX) single and combined anti-pregnancy effect. Mice in pregnancy d7 once scMTX 8,24 and 72mg · kg-1 can cause embryonic death, pregnancy d13 mortality were 18  0%, 55  5% and 60  3%. Determination of serum progesterone levels after administration, pregnancy d9 found no significant change, pregnancy d13 levels were significantly lower. Mice in pregnancy d7 ~ 9 injection of MTX24mg · kg-1 for three consecutive days caused all embryonic deaths. hCG and progesterone can antagonize the anti-early pregnancy effect of MTX. RU486 can enhance the anti-pregnancy effect of MTX, suggesting a synergistic effect of the two drugs in combination with anti-early pregnancy.