Lactobacillus plantarum Dad-13 that isolated from “dadih” (traditional Indonesian fermented milk) has been known as probiotic, while sweet potato fiber has been proven as an effective prebiotic. The objective of this study was to evaluate the potency of Lactobacillus plantarum Dad-13 and sweet potato fiber as immunomodulators in terms of intestinal secretory immunoglobulin A (sIgA) and splenocyte gamma-interferon (IFN-?). Sixty male Sprague Dawley rats (uninfected and infected) were divided into five groups: AIN-93, Indonesian children diet (ICD), Sweet potato fiber (SPF), SPF + Lactobacillus plantarum Dad-13 (SPFL), and fructooligosaccharides + Lacto-B (FOSL). After diet intervention, the rats were killed and sampled including intestinal fluid, spleen and caecal digesta. The results showed that soluble fiber such as sweet potato fiber could not increase the number of lactobacilli in infected rats, but could play a role in mucosal immune response through the increasing of sIgA. While, Lactobacillus plantarum Dad-13 contained in the combination with sweet potato fiber may has potency in systemic immune stimulation, because of the tendency to increase level of splenocyte IFN-? in infected rats.