Antigenic potential of DW-116, a newly synthesized fluoroquinolone, was examined by conduc-ting active systemic anaphylaxis (ASA), passive cutaneous anaphylaxis (PCA) and passive hemagglutination (PHA) tests. In ASA test, mild to moderate signs of anaphylactic responses were observed in the groups sensitized with low (2 mg/body) and high (10 mg/body) doses of DW-116 alone and the group sensitized with DW-116 plus adjuvant. Some moderate to severe anaphylactic reactions were observed in the group sensitized with a DW-116-bovine serum albumin (BSA) conjugate plus adjuvant when challenged with a DW-116-guinea pig senHn albumin (GSA) conjugate. However these reactions were considered to be a cross-reaction between BSA and GSA since similar reactions were induced when challenged by GSA alone. In heterologous PCA test using mice and rats, positive responses were not detected in any of the experimental groups. In PHA test, positive responses were observed in the groups sensitized with low and high doses of DW-116 alone and the group sensitized with DW-116 plus adjuvant. However, these responses were not considered to be drug-specific because some positive responses were also seen in the negative control group. From these results, it was concluded that DW-116 is not likely to have specific antigenic potential in clinical use.