Restriction fragment length polymorphisms (RFLPs) were employed to investigate genetic diversity and quantitative trait loci (QTL) for morphological characters on sorghum (Sorghum bicolor (L.) Moench). The objectives of this research were accomplished by studying two different sets of genotypes. One set was composed of 105 elite inbred lines (47 B- and 58 R-lines) and the other of 152 F[subscript]2:3 lines. In the R- and B-lines set, the objectives were to define the level of genetic similarity (GS) and relationships within these lines. In the 152 F[subscript]2:3 lines set, the objectives were to characterize QTL affecting morphological traits, compare QTL mapping in the F[subscript]2:3 to those obtained in F[subscript]2 populations, identify correspondence between QTL for height and the qualitative Dw loci, and identify regions defined by common RFLP loci affecting plant height in sorghum and maize;Average GS based on RFLPs was 0.67 for R-lines and 0.76 for B-lines indicating more diversity within the R-group. Cluster analysis of GS estimates from the entire set (105) of inbreds revealed separate groupings for R- and B-lines. There was a moderate positive correlation between GS and the coancestry coefficient (f) of these lines indicating that RFLP data can help quantify the degree of relatedness in sorghum germplasm;Eight out of ten linkage groups in sorghum were significantly associated with the morphological traits evaluated in the F[subscript]2:3 population. More QTL were identified per trait in the F[subscript]2:3 than in the F[subscript]2 generation. Around 69% of the QTL detected in the F[subscript]2 was also detected in the same region in the F[subscript]2:3 generation. Overall, highly correlated traits had most QTL coinciding at the same regions suggesting linkage and/or pleiotropic effects. Plant height QTL were identified to correspond with the Dw loci (dw1, dw2, dw3, and dw4) which control most of the variation in height. Also, a QTL for anthesis located on linkage group H may correspond with the maturity ma1 loci. In comparing sorghum and maize linkage maps, four orthologous regions were identified to affect plant height and other traits in both species.