We investigated the antioxidant, nitrite scavenging, immune-enhancing and antimicrobial effects of the Lentinus edodes fruiting body extracts (LEFB extract) cultivated in the solid state using corn cob. The CAT, SOD and GSH-Px activities in the LEFB extract (400mg)-fed group were approximately 1.70, 1.64, and 2.2 times higher than those of the control group. The nitrite scavenging activity was highest (86.4%) when the LEFB extract concentration was 600 μg/mL. The immune-enhancing and antimicrobial effects of LEFB extract after an experimental Bordetella bronchiseptica infection were examined. White blood and neutrophil in the LEFB extract (400 mg)-fed group were approximately 2.1 and 2.2 times higher, respectively, than those of the control group. The total leukocyte was 30% higher than that of the control group. The CD4 : CD8 ratio in the LEFB extract (200 mg)-fed group was increased approximately 54.3% compared to that of the control group. The levels of TNF-α and IFN-γ mRNA expression in the LEFB extract (400 mg)-fed group were approximately 49 and 50% lower than those of the control group. The bacteria and inflammatory cell in the LEFB extract (400 mg)-fed group were approximately 48.7 and 29% lower, respectively, than that of the control group. These results suggest that the LEFB extract may be useful in immune function improvement.