Cytoplasmic male sterility (cms) is determined by nuclear-cytoplasmic interactions. Up tonow, most studies are focused on the comparison of cytoplasmic DNAs of male-sterile lines and male-fertilelines, and analysis of nuclear DNA has not been documented yet. In order to find out the possible difference innuclear genome of male-sterile line A1 Tx623 and corresponding male-fertile line Tx623 of sorghum, randomamplified polymorphic DNA (RAPD) approach was used to analyze their cytoplasmic and nuclear genomes.Total DNAs of them were amplified at first to screen primers, which were able to generate reproducible bandsspecific to male-sterile line or male-fertile line. Then the selected primers were used to amplify their mitochon-drial DNA (mtDNA) and chloroplast DNA (cpDNA). The origins of all the polymorphic fragments were ana-lyzed. After ruling out those amplified from cytoplasmic DNA, seventeen polymorphic fragments were deter-mined to be amplified from nuclear DNA. These fragments originated from nuclear DNA indicate that diffe-rences in sequence exist between the nuclear DNA of male-sterile line and male-fertile line of sorghum, whichdo not agree with the traditional standpoint that they have identical nucleus.