Objective: Studies have examined the impact of race on infertility, but few have compared ethnic differences in infertility within a given race. We sought to determine whether infertility etiologies differ between Black ethnic subgroups. Design/Setting: Retrospective study in an urban safety net hospital. Population: Women seeking infertility care between 2005-2015. Methods: Charts of women with infertility and PCOS ICD-9 diagnoses were reviewed to confirm diagnoses. Data was stratified by race and subsequently by ethnicity to evaluate differences in infertility etiologies between Black American, Haitian, and African women. White American women were used as the comparison group. Main outcome measures: Infertility diagnoses between ethnic groups. Results: A total of 358 women met inclusion criteria including 99 Black American, 110 Black Haitian, 61 Black African, and 88 White American women. Anovulation/polycystic ovarian syndrome (PCOS) was the most common diagnosis in each ethnic group, accounting for 40% of infertility among White American, 57% among Black American, 25% among Haitian, and 21% among African women. There were no significant differences in individual infertility diagnoses between Black and White women. Between ethnic subgroups, multivariate analysis showed significantly higher odds of infertility due to anovulation/PCOS in Black American women compared to African women (odds ratio [OR]=4.9; 95% CI=1.4-17.0). Compared to African women, higher odds of tubal factor infertility were observed in Black American (OR=4.7; 95% CI=1.16-18.7) and Haitian women (OR=4.0; 95% CI=1.1-14.0). Conclusions: Causes of infertility weren’t homogeneous across Black ethnic groups. Studies examining infertility should specify ethnic subgroups within race as this may affect results.