The angiopoietins are a class of growth factors that activate the Tie2 receptor and play important roles in the regulation of angiogenesis. Proper regulation of angiogenesis is required for both embryonic vascular development and physiological processes in the adult such as wound healing and the female reproductive cycle, while aberrant regulation of angiogenesis contributes to a number of pathological conditions. As a result, an increasing amount of attention has been directed toward analysis of the expression and function of the angiopoietins and Tie2. Mounting evidence suggests that not only does altered expression of these molecules play a pivotal role in processes requiring vessel growth and remodeling, but has been implicated in a variety of other biological and pathological processes as well. These data suggest that modulation of the Ang/Tie2 system may prove to be a desirable therapeutic goal in the treatment of a diverse array of pathological conditions.