Many biological processes involve globular transport proteins belonging to a family called lipocalins. The prominent feature in lipocalin structure is their specific tertiary conformation forming eight-stranded beta barrel with capacity to bind various ligands inside. The importance of lipocalins is evident from the list of vital substances (Hydrophobic ligands including vitamin A, steroids, bilins, lipids, pheromones etc.) that these proteins transport and from their high expression levels in various tissues. Among wide spectrum of lipocalins, Major Urinary Proteins (Mup) and Odorant Binding Proteins (Obp) are well known for their capacity to bind and carry odorants / pheromones and have been studied to detail in various mammalian models including mice, rats, and hamsters. However, many lipocalins (also including Mups) have previously been described with respect to their protective function in mammalian organism where they transport potentially harmful molecules to a degradation site (e. g. lysozomes) or straight out of the body. As most of lipocalins share similar tertiary structure, their potential role in both transport and excretion processes may be additive or complementary. In addition to a role of lipocalins in chemical communication this review presents lipocalins from the point of view of the "toxic waste hypothesis". This hypothesis assumes that members of lipocalins that are linked to a metabolic degradation of their ligands were an ideal source for natural selection during evolution due to an ability of potential receivers to detect lipocalin ligands levels as a signal by other individuals.