OBJECTIVE: To probe into the correlation between efficacy of chemotherapy in patients with metastatic colorectal cancer（ m CRC） and serum homocysteine（ Hcy） and tumor markers. METHODS: 76 patients with m CRC admitted into Beijing Friendeship Hospital Affiliated to Capital Medical University from Feb. 2018 to May 2019 were selected

all of whom were diagnosed as stage Ⅳ colorectal cancer. The therapeutic regimen of m FOLFOX6（ oxaliplatin +calcium folinate + 5-fluorouracil） combined bevacizumab was used for 4 courses of treatment

the efficacy was evaluated after treatment

the serum carcino-embryonic antigen（ CEA）

cancer antigen 199（ CA199）

cancer antigen 125（ CA125） and Hcy levels were detected before and after treatment after treatment; the relationship between changes and efficacy in CEA

CA199

CA125 and Hcy levels was analyzed by ordered logistic regression

the correlation between efficacy and CEA

CA199

CA125 and Hcy was detected by Spearman correlation coefficient method.RESULTS: Compared with before treatment

after treatment

the CEA

CA199 and Hcy levels of patients with partial remission were significantly reduced

the CEA and Hcy levels of patients in stable disease were significantly increased

and the CA199

CA125 and Hcy levels of patients in progressive disease were significantly increased

all with statistically significant differences（ P < 0. 05）. The difference in Hcy levels before and after treatment and the difference in CEA levels before and after treatment were the risk factors of clinical efficacy

the larger the difference

the worse the clinical efficacy

with statistically significant differece（ P < 0. 05）. The correlations between clinical efficacy and changes in CEA

CA199

CA125 and Hcy levels before and after treatment were ranked as CEA >CA199 > Hcy > CA125. CONCLUSIONS: Changes in serum CEA

CA199 and Hcy levels before and after treatment are related to the efficacy of chemotherapy in m CRC patients; this study has a certain clinical value.