Herbicide-resistant transgenic rapeseed (TG rapeseed) was developed by inserting phosphinothricin acetyltransferase (PAT, bar), a modified gene from the soil bacterium Streptomyces hygroscopicus, into the genome of a conventional variety of rapeseed (Youngsan). The TG rapeseed used for the test was confirmed to express the PAT gene by polymerase chain reaction (PCR) and immunostrip. Feeding tests were conducted with Cyprinus carpio to evaluate the environmental risk of TG rapeseed, including the herbicide resistant gene. C. carpio was fed 100% ground rape suspension, TG rapeseed, or non-genetically modified (GM) counterpart rapeseed (Youngsan). As a result, the feeding test showed no significant differences in the cumulative immobility or abnormal response between C. carpio samples fed on TG rapeseed and non-GM counterpart rapeseed. The 48 h-LC50 values of the TG rapeseed and the non-GM counterpart rapeseed were 3,376 mg/L (95 % confidence limits: 3,169 - 3,596 mg/L) and 2,682 mg/L (95 % confidence limits: 2,267 – 3,123 mg/L), respectively. The rape NOEC (no observed effect concentration) value for C. carpio was suggested to be 625 mg/L. Based on these results, there was no significant difference in the toxicity for non-target organisms (C. carpio) between the TG rapeseed and non- GM counterparts.