Abstract: High-resolution late replication banding patterns were obtained on prometaphase chromosomes of Bufo bufo gargarizans and Bufo raddei by treating cultured lymphocytes with 5-bromodeoxyuridine (BrdU).The characteristic late replication regions on each banded chromosome of Bufo bufo gargarizans,which can be easily distinguished from other chromosomes,have been observed.Precise comparison between two species highresolution late replication banding patterns indicates that all chromosomes of two species are highly homologous.These results show that under the same culture condition and at the same time when BrdU were incorporated into DNA,it is possible to research chromosome homology among different species by comparing replication banding patterns.