Blastokinin or uteroglobin (UG) is a steroid-inducible, evolutionarily conserved, secreted protein that has been extensively studied from the standpoint of its structure and molecular biology. However, the physiological function(s) of UG still remains elusive. Isolated from the uterus of rabbits during early pregnancy, UG is the founding member of a growing superfamily of proteins called Secretoglobin (Scgb). Numerous studies demonstrated that UG is a multifunctional protein with anti-inflammatory/ immunomodulatory properties. It inhibits soluble phospholipase A₂ activity, binds and perhaps sequesters hydrophobic ligands such as progesterone, retinols, polychlorinated biphenyls, phospholipids and prostaglandins. In addition to its anti-inflammatory activities, UG manifests anti-chemotactic, antiallergic, antitumorigenic and embryonic growth-stimulatory activities. The tissue-specific expression of the UG gene is regulated by several steroid hormones although a nonsteroid hormone, prolactin, further augments its expression in the uterus. The mucosal epithelia of virtually all organs that communicate with the external environment express UG and it is present in the blood, urine and other body fluids. While the physiological functions of this protein are still under investigation, a single nucleotide polymorphism in the UG gene appears to be associated with several inflammatory/autoimmune diseases. Investigations with UG-knockout mice revealed that the absence of this protein leads to phenotypes that suggest its critical homeostatic role(s) against oxidative damage, inflammation, autoimmunity and cancer. Recent studies on UG-binding proteins (receptors) provide further insight into the multifunctional nature of this protein. Based on its anti-inflammatory and anti-allergic properties, UG is a potential drug target.