Genetic distances and phylogenetic clustering are calculated for sympatric populations of Rhipicephalus pusillus (Gil Collado) 1939 ticks, using cuticular hydrocarbon analysis and several statistical tools (stepwise discriminant analysis, Nei’s genetic distance using different sets of compounds, and Cavalli-Sforza’s Brownian motion model). Discriminant analysis on genic frequencies permits the detection of the most ancient geographic relationships between the populations, while the genetic distance method determines current evolutive affinities. However, methods based on quantitative estimation provide a poor resolution. Genetic distances are very high in the populations studied, suggesting a strong reproductive isolation of the specimens involved.