Objective To study the differential display of promyletic leukemia cell lines induced and non-induced by all-trans ret inoid acid (ATRA). Methods cDNA fragment was obtained by revers e transcription-polymerse chain reaction (RT-PCR) with total RNA extracted from promyletic leukemia cell lines. The amplified cDNA fragment was confirmed on non -denaturing polyacrylamide gel. Results With 24 primer combinat ions, we amplified a total of 541 bands, the mean number of bands obtained per l ane was 23, and 36 bands were found with obvious differnce. Conclusions mRNA differential display is effective to detect and characterize alte red gene expressions in promyletic leukomia cell lines induced and non-induc ed by ATRA.