We investigated the effect of Lactobacillus acidophilus strain L-55 isolated from infant feces on experimental allergic rhinitis in BALB/c mice. The heat-treated cells of strain L-55 were orally administrated for 4 consecutive weeks to mice sensitized by ovalbumin (OVA), and nasal symptoms (sneezing and nasal rubbing) induced by OVA challenge were evaluated. Strain L-55 at doses of 1 and 10 mg cells/mouse significantly inhibited nasal symptoms by repeated administration over a period of 2 weeks. Furthermore, we measured the level of OVA-specific IgE titers in the serum by passive cutaneous anaphylaxis (PCA) reaction. PCA titers in the sera from mice administrated strain L-55 were significantly lowered compared with the control. These results suggest that oral administration of strain L-55 may be useful for alleviating the nasal symptoms of allergic rhinitis.