Breast cancer (BC) is the leading cause of cancer-related mortality among females worldwide, and angiogenesis plays a crucial role in BC progression. 27-Hydroxycholesterol (27HC) is an endogenous selective estrogen receptor modulator, which promotes the growth and metastasis of BC. Here, we further found that, 27HC improved the angiogenic ability of BC in a VEGF-dependent manner. For the molecular mechanisms, on one hand, as an estrogen-like factor, 27HC enhanced the expression of VEGF by the classical ER alpha/VEGF signaling in ER-positive BC cells; on the other hand, in both ER-positive and ER-negative BC cells, 27HC enhanced the generation of ROS, which in turn activated the STAT-3/VEGF signaling in an ER independent manner. Either blocking the generation of ROS or knockdown of STAT-3 attenuated the 27HC-induced autocrine of VEGF and angiogenesis. These findings not only suggested a mechanism whereby 27HC enhanced the angiogenesis, but also helped to recognize the 27HC as a novel potential harmful factor in BC, especially in the menopause patients. (C) 2016 Elsevier Ireland Ltd. All rights reserved.