采用ＭＴＴ比色法检测了甲酰四氢叶酸增强５－氟尿嘧啶对人食管癌Ｅｃａ－１０９细胞的细胞毒效应。结果表明，５－Ｆｕ联用ＬＶ时，５－Ｆｕ与ＬＶ同时给药的细胞毒效应比单用５－Ｆｕ提高４～７％；而延迟ＬＶ给药时比单５－Ｆｕ提高６～１５％，其中５－Ｆｕ浓度为１００μｇ／ｍｌ组与单５－Ｆｕ组比较，差异具有显著性。结果显示，ＬＶ可以增强５－Ｆｕ的细胞毒效应，这种效应可能与５－Ｆｕ的浓度及ＬＶ的给药时机有关。 MTT assay was used to detect the cytotoxic effect of leucovorin on human esophageal cancer Eca-109 cells induced by 5-fluorouracil. The results showed that when 5-Fu was combined with LV, the cytotoxic effect of 5-Fu and LV administration was increased by 4-7% compared with 5-FU alone, and increased by 6-15 compared with 5-FU alone after delayed LV administration. %, in which the concentration of 5-Fu was 100 μg/ml compared with the single 5-Fu group, the difference was significant. The results showed that LV can enhance the cytotoxic effect of 5-Fu, and this effect may be related to the concentration of 5-Fu and the timing of administration of LV.