The objective of this study was to determine the effects of feeding Chinese herbal ultra-fine (CHU) powder to sows during the last week of gestation and during the lactation period on immunological performance of the offspring. In this experiment, 15 pregnant sows (mean BW = 235.6 ± 3.7 kg) were randomly assigned to 1 of 3 treatments including no additive (Control), 0.75% CHU powder (Group A), or 1.5% CHU powder (Group B) added to a maize- and soybean meal-based diet. Blood from 10 piglets per group was collected at d 7, d 14, or d 21 of age to measure serum metabolites, lymphocyte proliferating activity, and serum antibody and cytokine concentrations. Dietary supplementation of sows with CHU powder increased (P < 0.05) serum concentrations of total protein, albumin, and triglycerides of offspring, whereas the concentration of glucose was reduced (P < 0.05) compared with Controls. The CHU powder enhanced (P < 0.05) serum concentrations of IgG in Group B offspring on d 7 and IgM in Group A offspring on d 7 and d 14, increased IL-10 in Group A offspring on d 7, as well as IL-2 in offspring from Groups A and B on all days of determination. The CHU powder increased interferon gamma in Group A offspring on d 14 and in Group B offspring on d 14 and d 21, and increased tumor necrosis factor alpha in offspring of Group A on d 14 and in Group B on all days surveyed. Compared with Controls, a greater number (P < 0.05) of T lymphocyte subpopulations were detected in Group A and B offspring including CD4+ cells in Group A on d 7 and d 21, CD4+ cells in Group B on d 14 and d 21, and CD8+ cells in Group A on d 7 and d 14. Collectively, these findings indicate a beneficial effect of CHU powder treatment of sows in later gestation and during lactation on serum metabolism and cellular and humoral immune responses of their offspring.