Macrophages are ubiquitous cells with an impressive range of functions. These include phagocytosis and coordination of the initiation and effector phases of immune responses, as well as production of bioactive proteins and lipids that profoundly influence cell growth, differentiation and function. Macrophages are highly individualized in tissues, where their activities are a reflection of targeting by systemic and local environmental signals. This review focuses on recent studies where uterine macrophage population densities and distribution have been mapped, chemotaxis, differentiation and activation have been investigated and production of potent effector molecules has been explored. Evidence supporting a major role for female sex steroid hormones and the uterine growth factors they control in governing these features of uterine macrophages is presented.