Malignant ascites is a common and devastating complication of late stage epithelial ovarian cancer (EOC) that features dysregulated, leaky blood vasculature. Moughon and colleagues show that tumor-associated macrophages (TAM) contribute dominantly to the vascular pathology of EOC malignant ascites. Consequently, blocking TAMs' functions by a selective CSF1R kinase inhibitor (GW2580) reversed the vascular leakage and improved vascular perfusion as indicated by the increased number of perfused, blood carrying (lectin, red) capillaries (CD31⁺, green). For details, see article by Moughon and colleagues on page 4742.