Pre-eclampsia is a hypertension disorder during pregnancy, significantly affects maternal morbidity and mortality worldwide. A Case-control research was done on 100 pregnant mothers as respondents: 50 case (pre-eclampsia) and 50 control groups (healthy pregnant mothers). Selected case the following characteristics: were patients that visited the Syamrabu Bangkalan Public Hospital; were third-generation Madura natives; aged between 20-40 years old; had a gestational age of over 20mgg; had blood pressure above 140/90mmHg; and single pregnancies. Control had the following characteristics: were healthy pregnant women without pre-eclampsia or chronic hypertension; were third-generation Madura natives; had a gestational age of over 20mgg; aged between 20-40 years; and without pregnancy complications. The results showed of those with PE, 45 had the AA genotype (homozygote) (90%), five had AC (heterozygote) (8%) and one had CC (homozygote) (2%). As for those without PE, 33 had the AA genotype (homozygote) (73.3%), 11 had AC (heterozygote) (26.7%), none had CC (homozygote) (0%). PE and non-PE cases mostly had the AA genotype (homozygote) and A alleles. AT1R 1166 A/C polymorphism was found to be a significant risk factor for pre-eclampsia, while potassium level had no significant effect on it. Meaning further research is needed on different ethnicities and races.