Abstract: Microcapsules of Lactobacillus brevis were prepared using spray drying technique and the resistance of the microencapsulated form of this microorganism to drying at high temperature and simulated gastrointestinal conditions were evaluated. The therapeutic effect of these microcapsules on the diarrhea of neonatal calf was also evaluated using ERIC-PCR. The results showed that the completely release of the encapsulated bacteria took place after 60 min in contact with simulated intestinal conditions. Microencapsulated bacteria were resistant at least for 90 min to simulated gastric juice (pH 1.2) or simulated intestinal juice (pH 7.2) and microencapsulated form of the microorganisms was more resistant to drying at 85°C than free form. ERIC-PCR profiles of diarrhea calves treated with probiotic capsules were similar to that of control health calves at 3 days post administration suggesting that administration of these probiotic capsules may have strong positive effect on the treatment of neonatal calf diarrhea.