Three different molecular marker technologies were used to determine the relatedness of 84 different lines of sorghum. Both racial characterization and geographical origin were found to be correlated with relatedness. In some cases, the region of origin was the more significant factor, where samples of different races from the same locality were more closely related than were samples of the same race from different localities. Wild sorghums were shown to have few novel alleles, suggesting that they would be poor sources of germplasm diversity. The results also indicated that Chinese sorghums are a narrow and distinctive group that is most closely related to race bicolor.