A glycoside the saponin was evaluated as a potential immunomodulator in various formulations. Hens were immunized three times orally with a bovine serum albumin (BSA) supplemented with 350 and 700 mg of the saponin. Birds in a positive control group were administered with solution of emulsified with an equal volume of Freund’s incomplete adjuvant. BSA-specific IgA antibodies in saliva and IgY antibodies in yolk were examined by ELISA. It was found that the birds inoculated with BSA in addition to 350 mg of saponin had a higher amount of BSA-specific IgA antibodies in the saliva and BSA-specific IgY antibodies in yolk, than hens that received lower doses of the glycoside. However, the total IgY content in yolk was higher in BSA + 700 mg of saponin-treated hens as compared to chickens immunized with lower dose of this mixture. These results suggest that saponin is useful as an oral adjuvant or immunomodulator for hens.