This study was carriet out to evaluate the acute intravenous toxicity and antigenicity of Guamerin, newly developed by Mogam Biotechnology Research Institute (MBRI). In acute intravenous toxicity test, ICR mice were administered intravenously with single dose of 1,000mg/kg, and body weights and clinical signs were observed for 14 days. No dead animal, clinical signs, body weight change and abnormal autopsy findings were found in control and Gumerin treated group. Therefore, the 50% lethoal dose (LD50) of Guamerin for ICR mice was more than 1,000mg/kg on intravenous route for male and female. And the antigenic potential of Guamerin was examined by active systemic anaphylaxis(ASA) and passive cutaneous anaphylaxis(PCA) tests. In the ASA test, low and high doses (10 and 100ug/animal, respectiwely) of Guamerin were administed subcutaneously to guinea pigs for 9 times 3 weeks. All experimental groups showed negative responses whereas the positive control group given ovalbumin plus Freunds complete adjuvant (FCA) showed severe anaphylactic responses. PCA test using rats with mice anti-serum against Guamerin, low and high doses(10 and 100 ug/animal, respectively) of Guamerin were administered to mice for 9 times in 3 weeks. The anti-serum against Guamerin was administed intradermally at the back of rats, however, any positive responses were not detected in the experimental groups. These results strongly indicate that Guamerin does not induce IgE production and is not a PCA reaction inducer under these experimental conditions.