Three groups of gestating gilts and sows (Exp. 1; n = 98) were used to determine the effects of Pichia guilliermondii (Pg), a whole yeast product (CitriStim, ADM Alliance Nutrition), on dam and litter immune parameters. At breeding, gilts and sows were allotted to 1 of 3 treatments maintained through lactation: sow control (SC) diet or SC supplemented with 0.1 (S1) or 0.2% (S2) Pg. Pigs from groups 1 (Exp. 2) and 2 (Exp. 3) were weaned (21 d) and allotted in a 3 (SC, S1, or S2) × 2 [nursery with Pg (NPg) or without Pg (NC)] factorial arrangement in a randomized complete block design. In Exp. 2 blood samples were collected on days 5 and 28 postweaning for analysis. In Exp. 3, 36 pigs were individually penned and challenged with lipopolysaccharide (25 μg/kg BW intramuscular; 0 h). Individual BW, ADFI, and rectal temperature (RT) were collected at -48, -24, 0, 24, and 48 h and blood samples were collected at 0, 5, and 24 h for analysis. In Exp. 1, total neutrophil count (NEU) and neutrophil:lymphocyte ratio (NLR) were greater on day 110 of gestation (P < 0.05) in S1 than SC. At weaning there was a liner increase (P < 0.05) in NEU, NLR, and percentage of total leukocytes (PTL) that were NEU as level of Pg increased in sow diets. In Exp. 2, pigs from S1 had increased (P < 0.05) overall IgG than SC. The PTL that were eosinophils was greater in pigs from S2 fed NPg on day 5 than NC (P < 0.05) and increased in all pigs from S2 on day 28 (sow linear, P < 0.1). On day 28, total leukocytes and eosinophils were increased in pigs from SC [quadratic response (Q), P < 0.05]. In Exp. 3, a linear increase (P < 0.05) in ADFI was observed at -24 to 0 h, -48 to 0 h, and 24 to 48 h as the level of Pg increased in sow diets. There was a linear increase in RT at -48, -24, 0, and 5 h with increasing Pg inclusion in sow diets (P < 0.05). However, RT decreased more from 5 to 24 h in pigs from sows receiving Pg. The number of monocytes and PTL that were monocytes were higher in S2 compared to SC and S1 (P < 0.05). Also, NEU were reduced at 5 h in S1 (P < 0.05), NLR was lower in S2 at 0 h and S1 at 5 h, IL-1β concentration was greater in SC at 0 h and S1 at 5 h, and IL-6 concentration was greater in S2 at 0 h and S1 at 5 h (P < 0.05). Furthermore, blood urea N (BUN) was higher in NC at 0 and 5 h than NPg (P < 0.05). In conclusion, Pg appears to impact immune response criteria of sows and weaned pigs.