The use of inulinases provides an alternative to the chemical process of inulin hydrolysis to obtain fructose syrup, and can reduce processing steps, time, and costs in the food industry. The objective of this work was to screen the thermostable inulinases produced by yeast and yeast-like strains isolated from the Brazilian semi-arid region. Thermostability was studied at different temperatures (60 degrees C, 70 degrees C, 80 degrees C and 90 degrees C) and for increasing periods of time (0-50 min). Thirty-three microorganisms were tested, and 27 showed inulinase activity with specific activities ranging from 0.98 to 73.79 micromol/mg protein/min. Three strains (CCMB 300, CCMB327 and CCMB328) showed the desired combination of high specific activity and a small reduction in residual activity when submitted to heat treatment (>or=60 degrees C). Our results indicate that the inulinases produced by these three yeast strains from the Brazilian semi-arid region have great potential to be used for inulin hydrolysis in the food industry.