BACKGROUND: Borderline ovarian tumor (BOT) is an epithelial ovarian tumor with atypical epithelial proliferation without stromal invasion. BOTs may have an aggressive fashion with associated microinvasion feature, peritoneal “implants,” regional lymphadenopathy, and higher International Federation of Gynecology and Obstetrics (FIGO) stage. CD133 is cancer stem cells (CSCs) marker that promotes cell proliferation and tumor invasion through induction of nuclear factor kappa B and upregulation of MMP9. Aldehyde dehydrogenase 1A1 (ALDH1A1) is CSCs marker that promotes cell proliferation through the upregulation of c-MYC and cyclin-D1.
 AIM: The aim of this study was to investigate the correlation between CD133 and ALDH1A1 expression with FIGO stage. This research was performed as an analytic-observational with a cross-sectional design.
 METHODS: This research using a paraffin block of patients diagnosed as BOT in Hasan Sadikin Hospital Bandung. Samples were divided in two groups: FIGO stage IA and FIGO stage >IA. All samples were stained by immunohistochemistry CD133 and ALDH1A1. All data were analyzed using the Chi-square test with a significant level 5%.
 RESULTS: This study showed a statistically significant correlation between CD133 (p = 0.047) and ALDH1A1 (p = 0.042) expression with FIGO stage in BOT. Multivariate analysis showed there was no correlation between CD133 and ALDH1A1 in the affected of FIGO stage in BOT.
 CONCLUSION: CD133 and ALDH1A1 in BOT can be considered as a factor to predict the prognosis of BOT through predict FIGO stage.