In order to use the technique of Randomized Terminal Linker-dependent PCR(RDPCR) to detect DNA lesions of specific gene in vivo, rats were administered with potassium dichromate by i.p. injection and genomic DNA of lung were extracted. Single-stranded products were made by repeated primer extension, these products were ligated to a linker and thus amplified by primer P2 and PL. The final PCR products were detected by electrophoresis and Southern hybridization with DIG-labeled probe. The results showed that two hybridization bands for extron 7 of p53 gene were found with dosage of 20.0 mg/kg and 40.0 mg/kg indicating the DNA lesions of extron 7 of p53 gene, by potassium dichromate and there were two DNA lesion cites. The findings from this study provide evidences both for further investigation of mutational mechanism of hexavalent chromium and expansion on using RDPCR in toxicology.