A 5-wk trial with 96 ($(Landrace{ imes}Yorkshire){ imes}Duroc$) pigs ($BW=26.56{pm}0.42kg$) was conducted to investigate the effect of eugenol and cinnamaldehyde as feed additive in growing pigs. Pigs were assigned to 1 of 3 treatments in a randomized complete block design according to their sex and BW. Each treatment contained 8 replications with 4 pigs (2 gilts and 2 barrows) per pen. Treatments included: control (basal diet; CON); (basal diet+1,000 mg eugenol/kg; ET); (basal diet+1,000 mg cinnamaldehyde/kg; CT). Administration of eugenol and cinnamaldehyde did not did not affect (p>0.05) the growth performance and apparent total tract digestibility. Dietary CT and ET led to a higher (p<0.05) lymphocyte concentration compared with CON. The inclusion of CT and ET decreased (p<0.05) the fecal E. coli concentration (p>0.05). Pigs fed the diets supplemented with eugenol and cinnamaldehyde had reduced (p<0.05) $NH_3$ and $H_2S$ concentration throughout the experiment. In conclusion, results obtained in the present study indicated that supplementation of eugenol and cinamaldehyde had no effect on growth performance of pigs but exhibited lymphocyte-enhancing activity and decreased the fecal E. coli concentration and fecal noxious gas content ($NH_3$ and $H_2S$).