Feeding probiotics like live Saccharomyces cerevisiae var. boulardii (SB) in swine diets is recommended to promote a better health and reduce antibiotic use during critical periods like weaning. This study was conducted to determine if SB added in the diet of sows during the last 2 months of gestation and the 4 weeks of lactation may contribute to supporting health and performance of the piglets before and after weaning. Crossbred sows (n=45) from parity one to nine were allocated to two dietary treatments, Control (n=23) and SB (n=22). Sows in the SB group were fed the same standard gestation then lactation diet as the Control sows but with the addition of SB at 1×109 cfu/kg of feed. Piglets were weaned in challenging conditions (mixing of litters, no pen cleaning). SB supplementation in sow diets influenced faecal microbiota of the sows and their piglets. Five days after weaning, the alpha-diversity was lower (P<0.05) in piglets from SB sows than in piglets from Control sows. Analysis of microbiota with Partial Least Square Discriminant Analysis discriminated faeces from SB sows from that of Control sows at 110 days of gestation (37% error rate). Piglet samples could also be discriminated according to the diet of their mother, with a better discrimination early after birth (day 6 of lactation) than after weaning (day 5 post-weaning, 11% vs 34% error rate). Five days after weaning, piglets had greater white blood cell count, plasma haptoglobin and oxidative stress than before weaning (P<0.001). Nevertheless, SB supplementation in sow diets had no effect (P>0.05) on most of health criteria measured in blood and growth performance of piglets during lactation and the post-weaning period. Moreover, dietary supplementation of SB to sows did not elicit any changes (P>0.05) on their reproductive performance, metabolic and health status, nor in the immunoglobulin and nutrient content of colostrum and milk. In the present experimental conditions, feeding SB to sows influenced sow and piglet microbiota with no consequences on health and performance.