Blood vessels perform critical functions in both health and disease. Understanding how vessels form, pattern and respond to damage is essential. However, labeling and imaging the vasculature to ascertain these properties can be difficult and time-consuming. Here, the authors present a novel methodology for rapidly and efficiently labeling whole vascular networks in vivo by exploiting the fluorescent properties of Evans blue. By combining the labeling with fluorescence microscopy, this method enables visualization of whole tissue vasculature for a fraction of the time and cost compared with traditional methods.