Thermal resistance of dried bacterial spores against dry heat was determined. Spare suspensions of Bacillus subtilis var. niger ATCC 9372, Bacillus stearothermophilus Oxoid Code BR 23 and Clostridium sporogenes ATCC 19404 were located on aluminium strips, dried in electric oven under vacuum at room temperature for 10 minutes. The aluminium strips were laid in the middle of gas flow (hot air and superheated steam) with the velocity of 6 m/sec and heated at $120^{circ}C$ for 180 seconds. The calculated D-values showed that there were no remarkable differences in the heat resistance of bacterial spares between $R.H.leqq0.012$ and R. H.=0.51. Furthermore the thermal resistance of B. subtilis spores to dry heat was greater than that of B. stearothermophilus.