Molecular phylogenetic analysis, based on the 18S rRNA partial gene, showed the position of Spirocerca vulpis and Dirofilaria immitis isolates detected in red foxes (Vulpes vulpes) from southern France. The evolutionary history was inferred by using the maximum-likelihood method based on the Tamura-Nei model. The tree with the highest log-likelihood value (–2408.13) is shown. Initial tree(s) for the heuristic search were obtained automatically by applying neighbor-joining and BioNJ algorithms to a matrix of pairwise distances estimated using the maximum composite-likelihood approach and then selecting the topology with superior log-likelihood value. The analysis involved 22 nucleotide sequences. There were 935 positions in the final dataset.