HM10411 is a recombinant granulocyte-colony stimulating factor (rG-CSF) that has been developing as a drug for neutropenia. In this study, antigenic potential of HM10411 was examined by active systemic anaphylaxis (ASA) in guinea pigs and passive cutaneous anaphylaxis (PCA) in guinea pig-guinea pig system. HM10411 was subcutaneously administered at 0,5, and 50 mg/kg and also as a suspension with adjuvant (50 mg/kg+FCA). Ovalbumin (OVA) as a suspension with adjuvant was used to induce positive control responses. In the ASA test, no symptoms except urination and evacuation that were considered as physiological phenomena were observed at 0 and 5 mg/kg. Two of 5 animals at 50 mg/kg showed sneering, dyspnea, or cyanosis. All animals in the adjuvant mixture group showed severe symptoms of anaphylatic shock and 3 of them died. In the PCA test, no antibody against HM 10411 was detected in the sera from the animals sensitized with 0 or 5 mg/kg. Only 1 serum sample from the animals immunized with 50 mg/kg showed positive reaction against HM10411, while all 5 sera collected from the HM10411 and FCA mixture group contained the HM10411-specific antibodies. These results suggest HM10411 is considered to have antigenicity In guinea pig.