Introduction:When the drinking water of many species of ducks is changedfrom freshwater to saline, their salt glands hypertrophy and the principal cells showed numerous lateral cell evaginations and abundant mitochondria, enhancingtheir capacity to excrete salt. Aim of the work:The purpose of this investigation was to demonstrate and evaluate the anatomical, histological, and ultrastructural adaptations of the salt gland of the domestic female ducks associated with high salt osmotic stress. Material and methods: The present study was carried out on two groups of female domestic ducks and one group of wild ducks. Where as one group of domestic ducks was exposed to osmotic stress; imposed by replacing drinking tap water with 1% sodium chloride solution for two consecutive weeks. Morphometric measurements as well as histological and ultrastructural aspects of the salt glands were considered. Results: The investigation revealed that the weight and size of the salt glands of the salt-stressed ducks were markedly heavier and larger in comparison to those of the control and wild ducks. The number and the diameter of secretory lobules as well as the length of secretory tubules of the salt-stressed group were greater compared to the control ones.The degree of the proliferation and differentiation of the peripheral cells was distinctly greater for the salt-stressed than the control and wild ducks. The basal and lateral surfaces of the fully specialized secretory cell type in the salt-stressed and wild birds were obviously amplified and in many cases the folds of adjacent cells meshed with one another forming an elaborate complex of extracellular spaces and intracellular compartments. The cytoplasm of the fully specialized principal cells displayed abundant endoplasmic reticulum, numerous well developed mitochondria and deeply well developed basal foldings which increase the absorptive surface. Conclusion: The recorded peculiar features of the salt glands of the salt-stressed birds may be presented as an adaptive features to satisfy its special demands to eliminate the remarkable increased levels of sodium chloride load effectively. Key words: Histology, Supraorbital salt gland, Adaptations, Osmotic stress, Ultrastructure