This study was performed to elucidate the effects of Epimedii Herba on the antibody responses in mice immunized by Ovalbumin (OVA). Antibodies in serum were detected in male ICR mice treated with the aqueous extract of Epimedii Herba at a dosage of 40, 120, and 360 mg/kg orally for 2 weeks. Effects of AEEH on antibody forming responses were measured by enzyme linked immunosorbent assay (ELISA) of immunoglobulin (Ig) levels in serum collected 7 days after priming with OVA in complete Freund,s adjuvant (CFA). The results were as follows; 1. Epimedii Herba slightly decreased body weight gain. 2. Epimedii Herba significantly increased the relative spleen weight. 3. Epimedii Herba significantly increased total serum IgG levels. 4. Epimedii Herba significantly enhanced total serum IgG1 levels. 5. Epimedii Herba significantly increased total serum IgG2a levels. 6. Epimedii Herba markedly increased total serum IgM levels. These findings demonstrate that Epimedii Herba significantly enhances serum antibody production after priming with OVA in CFA, and suggest that Epimedii Herba may prevent the host from microbial infections.