Lactobacillus brevis ATCC 8287 is a potential probiotic lactic acid bacterium containing an S-layer, which makes it an interesting vaccine vector candidate. The aim of this study was to investigate the effects of L. brevis on growth performance and immune response in newly weaned piglets. Twenty piglets were assigned into two groups (treatment and control). The treatment group (n = 10) was fed 1x10¹⁰L.brevis daily for three weeks.  An equivalent amount of probiotic free-vehicle was provided as a placebo for the control group (n=10).  Health status and weight gain was monitored during the trial.  Blood and stool samples were collected at the beginning and the end of the trial and samples of the intestinal mucosa and luminal contents were collected at slaughter. The presence of L. brevis in stool samples was determined with bacterial isolation and S-layer specific PCR, and the abundance of total bacteria and L. brevis in digesta was investigated with quantitative PCR. Intestinal biopsy samples were sectioned for histopathological evaluation and immunofluorescence detection of L. brevis.Intestinal mucosal samples were analyzed for cytokine gene expression. Serum IgG and IgA concentrations were measured with ELISA. The results of the feeding trial will be discussed.