Key diagnostic morphological features for identifying Reticulitermes flavipes, R. virginicus, R. tibialis, and R. hageni collected from Oklahoma were identified and compared. Stepwise principle component analysis identified nine features useful for species determination. These features successfully identified 100% of R. tibialis and R. hageni specimens. However, fourteen soldier features for R. flavipes and R. virginicus, including pronotum width, showed interspecific overlap. Among soldiers whose species identification was confirmed with alates, the ratio of soldier head capsule length without mandibles to head capsule width separated these two species. Analysis of R. flavipes and R. virginicus features identified five descriminant factors that are useful in separating these two sympatric species. However, no factor was 100% definitive in separating these two species. Utilization of these five descriminant factors resulted in 88.89% and 82.61% correct identification of R. flavipes and R. virginicus, respectively. Correct species identification based only on soldiers remains tentative.