Greenhead flies of the Tabanus nigrovittatus complex from Massachusetts salt marshes were identified as T. nigrovittatus Macquart and T. conterminus Walker using the morphometric model developed by Sofield et al. Four body measurements from a total of 5,983 female flies collected over 2 consecutive years yielded canonical scores producing a unimodal rather than the expected bimodal distribution. The lack of bimodality indicated that both species were not present at the study site. This was substantiated by cuticular hydrocarbon (CHC) analysis of a subsample of these specimens. Fifteen, female flies of the Tabanus nigrovittatus complex from the same site were identified to species using the Sofield et al. morphometric model and validated using CHC analysis. Two individuals of the T. nigrovittatus complex were identified incorrectly as T. conterminus by the morphometric model. The tendency of this model to incorrectly classify some individuals of T. nigrovittatus as T. conterminus brings into question the identity of the Walker syntypes of T. conterminus. Based on CHC analysis, our study shows that both species coexist within our study area.