Abstract The essential oils of Lippia alnifolia Schau. and L. aff. gracillis H.B.K. from northeast Brazil were analyzed by GC/MS. Z. alnifolia oil was found to contain limonene (47.2%) and piperitenone oxide (44.6 %) as major components. The oil of L. aff. gracillis contained p-cymene (14.5%), Î³-terpinene (10.6%) and carvacrol (38.4%) as dominant constituents.