A 6-wk study with 50 birds was conducted to investigate the effects of a dietary supplemental probiotic on morphometric parameters and yield stress of the tibia. Twenty-five 1-d-old broiler chicks were assigned to a control or an experimental diet containing Bacillus licheniformis and Bacillus subtilis (BioPlus 2B, CHR Hansen BioSystems, Denmark, Ugur Ecza Deposu, Turkiye Distributoru, Adapazari 41400, Turkey; each containing 2.3 x 10(8) cfu/g of spores) supplemented to the starter and finisher diets at 500 g/1,000 kg of feed. Each diet was replicated 5 times with 5 birds in each replicate. Tibiotarsi weight, length, and weight/length index, robusticity index, diaphysis diameter, modulus of elasticity, yield stress parameters, and percentage Ca content were not affected by the dietary supplementation of probiotic, whereas thickness of the medial and lateral wall of the tibia, tibiotarsal index, percentage ash, and P content were significantly improved by the probiotic. Medullary canal diameter of the tibia of the birds fed the control diet was significantly greater than that of birds fed the probiotic diet. There was no treatment impact on live performance of the birds throughout the 6-wk feeding trial.