Abstract: This study aimed to evaluate the effects of dexatrol antibiotic and peppermint oil with different concentrations as a disinfectants on infected silkworm Bombyx mori larvae with bacteria by studying their effects on some biochemical characters of larvae as the protein enzymes activity; aspartate transaminase (AST), alanine transaminase (ALT), Total Soluble Protein (TSP) and free radical biomarkers; lipid peroxidation (MDA) and Protein Carbonyl Content (PCC). It found that, most concentrations enhanced the enzymes activity and decreased the effects of free radical on lipid and protein of larval haemolymph compared with the control group, especially dexatrol concentration (0.4%) and peppermint oil concentrations (0.5 and 0.25%) revealed the best results significantly.