This study examined the effect of Lactobacillus plantarum ONRIC b 0240 (L.p.b 0240) on the amounts of salivary and fecal IgA in adult volunteers. A double-blind comparative study was conducted on healthy adult volunteers. Thirty subjects were randomly divided into three groups, control group, L.p.b 0240 (2x109 CFU) group and L.p.b 0240 (2x109 CFU) group, and their diets were supplemented for 3 weeks. Twenty-six subjects completed the study. The results show the salivary IgA secretion rate was significantly higher for the L.p.b 0240 group than that of the control group. Furthermore, the amount of fecal IgA was higher in the L.p.b 0240 group than that of the control group, but not significantly. In addition, no adverse reaction was observed after oral administration of L.p.b 0240 during the study. These results suggest that L.p.b 0240 may con- tribute to the host defense through the enhancement of the mucosal immune function.