AIM: To explore the effect of single nucleotide polymorphism (SNP) of breast cancer susceptibility gene 1 (BRCA1) on chemotherapy sensitivity and survival prognosis of patients with metastatic esophageal squamous cell carcinoma. METHODS: A total of 153 patients with newly treated metastatic esophageal squamous cell carcinoma who were admitted to Suzhou Science and Technology City Hospital from June 2016 to February 2020 were included and administered with cisplatin combined with capecitabine chemotherapy. Before the first chemotherapy, 5 mL of venous blood was collected to extract DNA, and the TaqMan probe method was used to detect the genotypes of the BRCA1 gene rs8176318G/T, rs799917T/C and rs1799966T/C polymorphic loci. The objective response rate (ORR) and overall survival (OS) of different genotypes were analyzed. RESULTS: Rs799917T/C polymorphism was closely related to the chemosensitivity of metastatic esophageal squamous cell carcinoma. The chemotherapy response rates of TT, TC and CC genotypes increased gradually (TT 22.5%, TC 38.6%, CC 55.3%, χ