The natural resistance of heartwood from thirteen forest species (six of Tropical Rain Forest and seven of Pine-Oak Forest) to subterreanean termites Heterotermes sp. Attack, was evaluated by field microtests. Small blocks (2.5 x 2.5 x 5 cm) of each species were settled in 4 racks made of a highly susceptible wood, following a latin square arrangement. The racks were placed on the soil of the test area, in a tropical deciduous forest of the Biological Station La Mancha, Veracruz, Mexico. The total exposure period was 15 months. Natural resistance was evaluated by means of termite damage, according to a visual-rating system with five categories. Tropical rain forest woods were more resistant than pin-oak forest woods. For certain species, differences in the rank of attack were found betqeen racks, possible causes of the variability are discussed. The classification of woods are: Highly Resistant: Guarea chichon, Swietenia macrophylla (Meliaceae); Quararibea funebris (Bombacaceae). Resistant: Pinus patula var. Longepedunculata (Pineceae); Lysiloma acapulcensis (Leguminosae). Moderately Resistant: Pinus patula, Pinus aff. Pseudostrobus (Pinaceae); Quercus acatenangensis (Fagaceae). Susceptible: None. Highly Susceptible: Quercus crassifloia (Fagaceae); Alnus jorullensis (Betulaceae). In the case of Pinus teocote (Pinaceae); Schizolobium parahibum (Leguminosae) and Licania platypus (Rosaceae) no conclusive results were obtained.