This study evaluates the use of spray drying to produce microparticles of Lactobacillus casei. Microorganism was cultivated in shaken flasks and the microencapsulation process was performed using a laboratory-scale spray dryer. A rotational central composite design was employed to optimise the drying conditions. High cell viability (1.1 x 10(10) CFU/g) was achieved using an inlet air temperature of 70 degrees C and 25% (w/v) of maltodextrin. Microparticles presented values of solubility, wettability, water activity, hygroscopicity and humidity corresponding to 97.03 +/- 0.04%, 100% (in 1.16 min), 0.14 +/- 0.0, 35.20 g H2O/100 g and 4.80 +/- 0.43%, respectively. The microparticles were spherical with a smooth surface and thermally stable. Encapsulation improved the survival of L. casei during storage. After 60 days, the samples stored at -8 degrees C showed viable cell concentrations of 1.0 x 10(9) CFU/g.