The essential oils from accessions of Lippia sidoides Cham. (Verbenaceae) were characterized by GC and GC/MS and investigated for their acaricidal activity against the two-spotted spider mite (Tetranychus urticae Koch). Twenty-nine compounds were identified with potential acaricidal activity. Glass receptacles were used as test chambers. For each dose and exposure time combination, three replicates were used. Each replicate consisted of 30 adult females of T. urticae, 10 mites in each leaf disk of Canavalia ensiformis placed in a Petri dish. Increasing amounts of oil or terpene were applied on a blotting paper strip, fixed on the inner surface of the glass recipient cover, corresponding to 2, 4, 6, 8, and 10 microL/L of air, respectively. Exposure periods were 24, 48, and 72 h. Data obtained in these experiments were submitted to probit analysis. The essential oil of L. sidoides, thymol and carvacrol exhibited potent acaricidal activity against T. urticae.