Dr Judah Folkman was frequently described as a highly compassionate physician who served his patients not only by performing surgery and offering them comfort and reassurance, but also by working tirelessly in the laboratory to find new approaches to the treatment of disease. His dedication to understanding the role of angiogenesis, the formation of new blood vessels, in human disease has given rise to new treatments for several diseases, including inflammatory diseases, vision-threatening diseases of the eye and, as will be emphasized in this Perspective, cancer.