Thermal and microbiological characteristics of beddings for swine were compared according to their depth and of addition of inoculums. Bedding was added to boxes at 0.25 (25D) and 0.50 m (50D), with three treatments: control (no inoculums); T1, with 250 g of Bacillus cereus var. toyoii at 8.4 x 10(7) CFU; and T2, with 250 g of a pool of B. subtilis, Bacillus licheniformis and Bacillus polymyxa at 8.4 x 10(7) CFU (250 g for 25D and 500 g for 50D). Mean temperatures were 28.5 +/- 3.9 at the surface and 35.2 +/- 8.9 inside the beddings. The most probable number (MPN) of thermophilic bacteria was higher for T1 and T2 than for the control (P < 0.05). The MPN of thermophilic bacteria and fungi was greater for 050 than for 025 (P < 0.05). The use of 25D without inoculums is recommended due to the reduction of thermophilic microbiota. (C) 2012 Elsevier Ltd. All rights reserved.