Leaves from sixty trees in five populations of Eucalyptus camaldulensis Dehnh. and one population of Eucalyptus melliodora A.Cunn. ex Schauer growing in Fars Province in the south of Iran were analyzed for quantitative and qualitative variation in essential leaf oils. Using the sequence variation of the external transcribed sequence of ribosomal DNA (ETS rDNA) region, the phylogenetic relationships among the populations were also studied. The results obtained were interpreted using statistical analysis, considering the nineteen abundantly found compounds. The main ones were 1,8-cineole followed by globulol, limonene, Î±-pinene, viridiflorol and p-cymene. As the distribution of terpenoid variables was not normal within the populations, data analysis by a non-parametric KruskalâWallis test showed significant changes in the essential oil components among the studied populations. Principal components analysis based on the relative amounts of the essential oil components indicated four chemotypes. Nucleotide sequencing of the ETS rDNA gave fragments of 504 base pairs and generated distinct patterns among the populations. Using the Neighbor-Joining procedure with bootstrapping support based on a pairwise distance matrix led to a phylogenetic tree with four clades. However, good agreement exists between the molecular and phytochemical outcomes found in the phylogenetic relationship of some populations.