Production of probiotic foods is increasing due to their health benefits. Various studies have shown that survival of probiotic bacteria decreases during storage, food processing and passing through gastrointestinal tract. Hence, employing various methods such as microencapsulation can improve their survival and increase their resistance against harsh conditions. Recently, application of prebiotics as encapsulating agents to maintain the maximum survival of probiotics has attracted researchers' attention. In this research prebiotic polysaccharides were extracted from acorn. Extracted prebiotic was then compared with inulin (commercial prebiotic) as encapsulating agents for Lactobacillus plantarum PTCC 1896 by spray drying method. Concentrations of 2, 3 and 4% acorns' prebiotic and 5, 10 and 15% of inulin were used as treatments for microencapsulation. Concentrations of 3% acorn prebiotic and 15% inulin as optimal treatments were selected and then morphology of free and encapsulated bacteria were investigated using scanning electron microscopy (SEM). The encapsulating agents protective effects on survival of bacteria in the simulated gastrointestinal tract, storage and some technological conditions such as high temperature and high NaCl concentrations were studied. The SEM images showed the encapsulated bacteria with inulin spherical shapes with a wrinkled surfaces that and morphology of encapsulated bacteria with acorn prebiotics had irregular shapes with depressed surfaces. Microencapsulation by acorn extracted prebiotic increased bacteria resistance under gastrointestinal simulation conditions and this increase was better than inulin. The survival rate reduction of bacteria in simulated intestinal conditions in free and microencapsulated bacteria with inulin and acorn was 1.68, 0.62 and 0.14 logarithmic cycle, respectively. The result during 40 days of storage in two temperatures of 4 and 28 °C showed that survival of encapsulated bacteria with extracted prebiotics from acorn in both temperatures was maintained until 8.90 logarithmic cycle and survival of encapsulated bacteria with inulin reduced to 7.52 in 4°C and to 6.19 logarithmic cycle at 28°C. Overall results showed that increasing of temperature during storage didn't have significant effect on reducing of bacteria survival in acorn (p 0.05), but had significant effect on bacterial viability in inulin (p 0.05). It was also found that microencapsuls had no protective effect against heat on bacteria. In salinity resistance test, sensitivity values of free and microencapsulated bacteria with inulin and acorn prebiotic at concentration of 5% salt were 2.80%, 15.85% and 19.60%, respectively. Collectively results showed that application of acorn prebiotic in comparison to inulin for microencapsulation of bacteria by spray drying method causes greater resistance and survival against stomach, intestines and storage conditions. Therefore, use of acorn prebiotic could be suggested for increasing bacterial resistance against gastric acid and enzymes in the gastrointestinal tract and bacteria release into colon. While the tested prebiotics (inulin and acorn) had no protective effect against temperature. Therefore, microencapsulation of L.plantarum PTCC 1896 by spray drying method using these prebiotics can not protect it against high temperature. It could be suggested to mix them with other thermal resistance substances or their chemical modifications which could be the objectives of future researches. Keywords : probiotics, prebiotics, acorn, inulin, microencapsulation, spray drying