Over 90-95% of serous ovarian cancers express folate receptor (FR)-alpha, making this receptor an ideal target for marking most ovarian cancers. Folate is the prototypic agonist at the FR-alpha with potential uses for imaging and targeted therapeutic strategies.Chemotherapy does not affect FR-alpha expression in ovarian cancer specimens examined by immunohistochemistry, so prior treatment is unlikely to affect utility of FR-alpha agonists as imaging or therapeutic agents.