This study was conducted to determine the effect of herbal additive (AV/AGP/10, Ayurvet Limited, Baddi, H.P., India, based on extracts of garlic, ginger, menthol, cinnamon, and thyme) on the growth performances, health status, and carcass quality of finishing pigs fed diets. Ninety-six pigs (48 barrows and 48 gilts) at 84 d of age (41.5 ± 2.7 kg BW) were allotted to 4 treatments (2 × 2 factorial arrangement with 0 and 0.05% Tylan40 (Elanco) and herbal additive (0 and 0.05% AV/AGP/10) based on a randomized complete block design with 8 pens (3 pigs per pen, 4 barrow and 4 gilt pens) per treatment. Body weight and feed intake were measured weekly. Blood samples were taken on d 37 to obtain plasma to measure tumor necrosis factor α (TNF-α), protein carbonyl, and immunoglobulins. On d 40, 32 pigs (1 pig from each pen and 8 pens per treatment) were euthanized to collect duodenal and jejunal mucosa layers for TNF-α, protein carbonyl, IgA, and IgG concentrations. Gut tissues from middle part of jejunum were obtained to measure villus height (VH), crypt depth (CD), villus width and VH/CD. Carcass traits were measured including backfat thickness (10th rib), loin pH, marbling score, loin color, and drip loss. Data were analyzed using the MIXED procedure in SAS with pen as the experimental unit (treatment and sex as fixed effects and BW as a random effect). Overall, antibiotic supplementation increased (P < 0.05) final BW (88.0 to 90.4 kg), ADG (1.176 to 1.225 kg/d), hot carcass weight (62.0 to 63.8 kg), and cold carcass weight (60.0 to 61.7 kg). Herbal supplementation tended to reduce (P = 0.079) ADFI (2.829 to 2.785 kg/d), tended to enhance (P = 0.060) G:F at wk 5 (0.430 to 0.460), and enhanced (P < 0.05) G:F at wk 6 (0.612 to 0.643). Backfat thickness, loin weight, loin color, marbling score, plasma TNF-α, and tissue TNF-α were not affected by factors. There were no interactions between 2 factors in all measurements. Collectively, antibiotic supplementation improves growth performance and carcass weight whereas herbal additive can potentially enhance feed efficiency if it is fed to finisher pigs longer than 4 wk regardless of the use of antibiotics.