Serous borderline ovarian tumors (SBOTs) represent group of tumors with cellular atypia and absent stromal invasion. Many studies support that SBOTs share similar molecular and genetic alterations with low-grade serous carcinomas, while high-grade serous carcinomas have a distinct pathway to carcinogenesis. Here we present a 55-year-old woman who underwent exploratory laparotomy and maximal debulking for SBOT. First recurrence was SBOT while second recurrence was low-grade invasive serous carcinoma. Recent molecular studies showed that molecular alterations detected in SBOTs were also present in low-grade serous carcinomas. In this manner, ovarian low-grade serous carcinomas are thought to evolve in a step-wise fashion from benign serous cystadenoma to SBOT and finally low-grade invasive serous carcinoma.