ETS-1 has been identified as a transcription factor involved in tumor angiogenesis, which is essential for the growth, invasion, and metastasis of solid tumors. This result prompted us to study whether ETS-1 works as an angiogenic mediator in ovarian cancers. Immunohistochemical staining revealed that ETS-1 was expressed in vascular endothelial cells and in cancer cells of ovarian cancers. There was a significant correlation between microvessel counts and both ETS-1 histoscores and ets-1 mRNA levels in ovarian cancers. Both ETS-1 histoscores and ets-1 mRNA levels increased with the progression of ovarian cancers. Furthermore, the 24-month survival rate of 30 patients with high ets-1 (high ETS-1 histoscores and high ets-1 mRNA levels) was 30%, while that of 30 other patients with low ets-1 (low ETS-1 histoscores and ets-1 mRNA levels) was 70%. There was a significant difference between the 24-month survival rates of the 30 patients with high ets-1 and the 30 with low ets-1. This indicates that ETS-1 might act as an angiogenic mediator in, and be a prognostic factor for, ovarian cancers.