Phylogenetic relationships among all described species and four subspecies (total of 21 taxa) of the spiny lobster genus Panulirus White, 1847, were examined with nucleotide sequence data from portions of two mitochondrial genes, large-subunit ribosomal RNA (16S) and cytochrome oxidase subunit I (COI). Multiple sequence alignments were subjected to maximum-parsimony, neighbour-joining, and maximum-likelihood analysis with Jasus edwardsii as the outgroup. Two major lineages within Panulirus were recovered by all three methods for both the 16S and COI alignments analysed separately and for the combined alignment. The first lineage included all species of Panulirus classified as Groups I and II by previous morphologically based definitions. The second included all species classified as Groups III and IV. Relationships within major lineages were not well resolved; the molecular phylogeny did not support separation of Group I from Group II or of Group III from Group IV. The degree of sequence divergence between different pairs of species was higher in pairwise comparisons between species in Group I/II (16S: 2.8–19.4%; COI: 12.4–31.8%) than in those between species in Group III/IV (16S: 5.3–13.2%; COI: 12.6–19.6%). This pattern suggests that the Group I/II lineage may represent an earlier radiation of species within Panulirus .