Inclusion Criteria:  Female patients > 18 years of age Have a primary diagnosis, or at high clinical suspicion, of primary ovarian cancer (of epithelial type), planned for primary surgical cytoreduction, interval debulking, or have recurrent ovarian cancer Good operative candidate as determined by clinical presentation and laboratory assessments Subject capable of giving informed consent and participating in the process of consent.  Exclusion Criteria:  Pregnant women as determined by urinary or serum beta hCG. Patients with a history of allergy to any of the components of OTL38, including folic acid Known FR-negative ovarian cancer Patients with a known allergy to Benadryl Previous exposure to OTL38 Vulnerable populations: the homeless, prisoners or not capable of participating in the consent process