Recent scientific interest in cancer associated fibroblasts (CAFs) has demonstrated their central role in tumour progression in models of pancreatic, breast and prostrate carcinoma. However, their origin and precise role in promoting tumour growth remain unclear. Previously, our lab has established concrete evidence that another important member of the tumour microenvironment – perivascular cells (including pericytes in dermal microvessels), directly promote the proliferation and differentiation capacity of normal epithelial cells in a novel, paracrine manner, quite independent of angiogenesis - a role they are most associated with1. These cells also exhibit a CD146+CD73+CD90+ MSC signature and a multi-lineage differentiation capacity giving rise to the fat, cartilage and bone lineages in vitro. In addition, ovarian cancer patients carrying the dermal pericyte gene signature are predisposed to having a higher risk of relapse and thus a lower overall chance of survival, indicating that pericyte activity is a strong predictor of cancer recurrence and mortality. Importantly, this high-risk patient group was distinct from the groups identified by an angiogenic signature, suggesting a more direct role for pericytes in increasing tumour growth. In keeping with this clinical observation, we were able to show for the first time that co-inoculation of pericytes significantly accelerated the tumour growth and metastasis of human ovarian cancer cells in immunocompromised mice. Pericytes were also able to enhance the intrinsic migratory, invasive and proliferative capacity of these cells in vitro. In summary, while suggesting that pericytes might represent a novel origin of the much elusive CAFs, these results present the possibility that pericyte-specific markers can be used for prognosis of ovarian cancer progression and survival. They also open the doors for further research into the origin, lineage and role of pericytes and related paracrine interactions within the epithelial tumour stroma.