This MiniReview is intended to provide an overview of the current knowledge regarding cytological, physiological, and molecular aspects of Uromyces fabae. For almost five decades this rust fungus has served as a model system to gain insight into the features characterizing an obligate biotrophic parasite. While earlier studies mostly focused on cytological aspects, later studies were concerned with biochemical and molecular characteristics. Despite the fact that there is still no stable transformation system available for any obligate biotroph, recent molecular analyses have provided new insights into this highly sophisticated interaction of a fungus with its host.