Objective: Preeclampsia is more prevalent in African American women than other races. GBS colonization rate in African American women is the highest among different races. We hypothesized there is an association between GBS colonization and preeclampsia among pregnant African American women. Study Design: We evaluated the relationship between GBS colonization and preeclampsia in 11,766 patients records (93% were African Americans patients) between 2010 and 2017. Results: The preeclampsia rate of GBS colonized patients (2.6%) was 59% less than that of GBS-negative patients (6.3%). This inverse correlation was independently significant after adjusting for other potential risk factors for preeclampsia: chronic hypertension, gestational diabetes mellitus and diabetes mellitus and other covariates. Further analysis among the patients without these risk factors also confirmed that the preeclampsia rate of GBS colonized patients (2.6%) was 55% less than that of GBS negative patients (5.7%). Similarly, patients with HSV+ or HIV+ had lower incidence of preeclampsia than those with HSV- or HIV-. Conclusions: The unexpected finding of an inverse relationship between GBS colonization and preeclampsia suggests that the maternal immune response to GBS infection may be beneficial in reducing preeclampsia among African American patients.