The foliar flavonoid content of 142 individual pine trees (Pinus leiophylla, P. chihuahuana and P. lumholtzii) was analyzed by paper chromatography and ultraviolet spectroscopy with the aim of determining the ability of foliar profiles of flavonoids to distinguish closely related pine species and to determine if Pinus chihuahuana should be recognized as a distinct species or as a variety of P. leiophylla. The flavonoid composition of needles was evaluated within and among the taxa using Principal Coordinates Analysis (PCO). The results support the recognition of P. chihuahuana at the species level. Contrary to other reports, the results from this study suggest that needles of the three studied species contain a much greater number and diversity of flavonoids than previously reported for species of Pinus.