Mostly Academic hospitals are in need for illustrations with a educational purpose. The residents in a hospital need to learn progressive surgery methods without all the side issues you can see on a photograph (blood, fat tissue, etc.). The illustration offers a clean view on the method itself.
Illustrations to reinforce a thesis. Images speak for themselves.
Illustrations to explain the operation, the disease, etc.
Illustrations to explain emergency care in companies or at home.
Illustrations to explain biology and other professions.
Illustrations, paintings for the walls of offices.
Medical Illustrations to use as guide tool on a website.