Microcapsulation is one of the best methods for maintaining quality of sensitive materials and it is a way to produce compounds with new properties. It is a useful tool for improving delivery of bioactive materials, especially probiotics, minerals, vitamins, phytosterols, and fatty acids. Microcapsulation can be used to protect sensitive substances from environmental harsh conditions, hide unfavourable sensory properties and enhance controlled release. The efficiency of encapsulation depends upon a variety of factors, including polymer concentration, polymer solubility and production methods. Vitamin D plays a significant role for human health, survival and fertility. Several studies have emphasized its role in preventing immune and infectious diseases. Generally, amount of vitamin D that is supplied to the body through food sources is not enough. This is the most important reason of the vitamin D deficiency epidemic. This vitamin enhances the absorption of phosphorus and calcium from the intestines and reduces their excretion from the kidneys and enhances the osteoporosis process. Therefore, its deficiency is one of the most important factors in the development of bone metabolism disorders. The aim of this work was to study the physicochemical properties, release profiles in gastric and intestinal conditions, and investigate effect of microcapsules containing vitamin D on living creatures. Production of gelatin-cress seed mucilage carriers was optimized using response surface methodology (RSM). The optimum values of microencapsulation efficiency, loading efficiency, production yield, upper phase absorption and turbidity were 66.73 ± 0.84, 48.46 ± 1.72, 70.32 ± 0.02, 0.054 and 180.1, respectively. The results showed that the ratio of biopolymers and the ratio of core to shell had significant effects on the efficiency and loading capacity. By increasing the ratio of the core to shell from 0.25 to 1, the loading efficiency increased to 60%. According to the results of scanning electron microscopy(SEM), non-spherical particles with a rough surface were obtained by mean size of 137.2 ± 3.2?m. The data of Fourier transform infrared (FTIR) spectroscopy confirmed formation of an ion electrosthetic response between the biopolymers and the presence of vitamin D within the microcapsules. The release values of gelatin-cress seed mucilage microcapsules were 28 and 70% in the gastric intestinal buffers, respectively. Vitamin was also entrapped using mucilage and isolated soybean protein and the best ratio of the biopolymers and the core to the shell were both 0.3. By increasing the ratio of the biopolymers, the encapsulation efficiency and loading capacity decreased. However, by raising the ratio of core to shell encapsulation efficiency and loading capacity increased as well. In vivo study was also performed on male rats to investigate the efficiency of microencapsulated in comparison to unprotected vitamin D for height, weight, blood vitamin D and blood glucose. The results showed that microencapsulation can significantly (p 0.05) enhance haematic and anatomical characters. Keywords: microcapsulation, mucilage, soy protein isolate, vitamin D, release